SUSE Linux Enterprise Server for SAP Applications 12 SP2 or newer

SAP HANA System Replication Scale-Out - Performance Optimized Scenario

SUSE® Linux Enterprise Server for SAP Applications is optimized in various ways for SAP* applications. This guide provides detailed information about how to install and customize SUSE Linux Enterprise Server for SAP Applications for SAP HANA Scale-Out system replication automation in the performance optimized scenario. It is based on SUSE Linux Enterprise Server for SAP Applications 12 SP2. The concept however can also be used with SUSE Linux Enterprise Server for SAP Applications 12 SP3 or newer.

Author: Fabian Herschel, Distinguished Architect SAP, SUSE
Author: Bernd Schubert, SAP Solution Architect, SUSE
Author: Lars Pinne, System Engineer, SUSE
Publication Date: 2018-11-19

1 About this Guide

1.1 Introduction

SUSE Linux Enterprise Server for SAP Applications is optimized in various ways for SAP* applications. This guide provides detailed information about installing and customizing SUSE Linux Enterprise Server for SAP Applications for SAP HANA scale-out system replication automation in the performance optimized scenario.

High availability is an important aspect of running your mission-critical SAP HANA servers.

The SAP HANA scale-out system replication provides for replication of all data in SAP HANA to a second SAP HANA system. The SAP HANA itself replicates all of its data to a secondary SAP HANA instance. It is an out-of-the-box, standard feature.

The recovery time objective (RTO) is minimized through the data replication at regular intervals. SAP HANA supports asynchronous and synchronous modes. The document at hand describes the synchronous replication from memory into memory of the second system. This is the only method that allows the cluster to make a decision based on coded algorithms.

1.2 Additional Documentation and Resources

Chapters in this manual contain links to additional documentation resources that are either available on the system or on the Internet.

For the latest SUSE product documentation updates, see http://www.suse.com/documentation.

Find white-papers, best-practices guides, and other resources at the

1.3 Feedback

Several feedback channels are available:

Bugs and Enhancement Requests

For services and support options available for your product, refer to http://www.suse.com/support/.

To report bugs for a product component, go to https://scc.suse.com/support/ requests, log in, and select Submit New SR (Service Request).

User Comments

We want to hear your comments about and suggestions for this manual and the other documentation included with this product. Where available, use the User Comments feature at the bottom of each page in the online documentation and enter your comments there.

Mail

For feedback on the documentation of this product, you can also send a mail to doc-team@suse.com. Make sure to include the document title, the product version and the publication date of the documentation. To report errors or suggest enhancements, provide a concise description of the problem and refer to the respective section number and page (or URL).

2 Scope of this Documentation

This document describes how to set up an automation of an SAP HANA scale-out system replication cluster installed on two sites based on SUSE Linux Enterprise Server for SAP Applications 12 SP2. This concept can also be used with SUSE Linux Enterprise Server for SAP Applications 12 SP3 or newer.

To give a better overview the installation and setup is subdivided into seven steps.

After the setup process you will have a SUSE Linux Enterprise Server for SAP Applications cluster controlling two 'swarms' of SAP HANA scale-out in a system replication configuration. The architecture is named the 'performance optimized scenario'.

SAPHanaSR ScaleOut Cluster
Figure 2: Cluster with SAP HANA SR - performance optimized

3 Planning the Installation

Planning the installation is essential for a successful SAP HANA cluster setup.

What you need before you start:

  • Software from SUSE: SUSE Linux Enterprise Server for SAP Applications installation media and a valid subscription for getting updates

  • Software from SAP: SAP HANA installation media

  • Physical or virtual systems including disks and NFS storage pools (see below)

  • Filled parameter sheet (see below)

3.1 Minimum Lab Requirements and Prerequisites

This section defines some minimum requirements to install SAP HANA scale-out.

Note
Note

The minimum lab requirements mentioned here are no SAP sizing information. These data are provided only to rebuild the described cluster in a lab for test purposes. Even for such tests the requirements can increase depending on your test scenario. For productive systems ask your hardware vendor or use the official SAP sizing tools and services.

Note
Note

Refer to SAP HANA TDI documentation for allowed storage configuration and file systems.

SAPHanaSR ScaleOut NFSPool 2+1
Figure 4: Simplified NFS share structure of a 2+1:2+1 SAP HANA system replication

Requirements with 3 SAP instances per site (2+1 : 2+1) - with a majority maker:

  • 6 VMs with each 32GB RAM, 50GB disk space

  • 1 VM with 2GB RAM, 50GB disk space

  • 1 shared disk for SBD with 10 MB disk space

  • 2 NFS pools (one per site) with a capacity of each 96GB

  • 1 additional IP address for takeover

SAPHanaSR ScaleOut NFSPool 3+2
Figure 5: Simplified NFS share structure of a 3+2:3+2 SAP HANA system replication

Requirements with 5 SAP HANA instances per site (3+2 : 3+2) - with a majority maker:

  • 10 VMs with each 32GB RAM, 50GB disk space

  • 1 VM with 2GB RAM, 50GB disk space

  • 1 shared disk for SBD with 10 MB disk space

  • 2 NFS pools (one per site) with a capacity of each 132GB

  • 1 additional IP address for takeover

The SBD based fencing needs up to 3 shared block devices.

SAPHanaSR ScaleOut SBDs 3+2
Figure 6: Additionally to the NFS shares: All cluster nodes need to have access to the SBD block devices

3.2 Parameter Sheet

The cluster organizing two SAP HANA 'swarms' is quite complex. The installation should be planned properly. You should have all needed parameters like SID, IP addresses and much more already in place. It is a good practice to first fill out the parameter sheet and then begin with the installation.

Table 1: Parameter sheet to prepare the NFS based setup
ParameterValue

Path to SLES for SAP media

SMT server or SCC account

Path to SAP HANA media

S-User for SAP marketplace

Node names site 1

Node names site 2

Node name majority maker

IP addresses of all cluster nodes

SID

Instance number

Service IP address

HANA site name site 1

HANA site name site 2

NFS server site 1

NFS share "shared" site 1

NFS share "data" site 1

NFS share "log" site 1

NFS server site 2

NFS share "shared" site 2

NFS share "data" site 2

NFS share "log" site 2

SBD STONITH block device(s)

Watchdog driver

3.3 Scale-Out Scenario and Resource Agents

To automate the failover, the High Availability Extension built into SUSE Linux Enterprise Server for SAP Applications is used. Two resource agents have been created to handle the scenario.

The first is the SAPHanaController resource agent (RA), which checks and manages the SAP HANA database instances. This RA is configured as a master/slave resource.

The master assumes responsibility for the active master name server of the SAP HANA database running in primary mode. All other instances are represented by the slave mode.

SAPHanaSR ScaleOut Cluster Resources02
Figure 7: Cluster resource agents and master/slave status mapping

The second resource agent is SAPHanaTopology. This RA has been created to make configuring the cluster as simple as possible. It runs on all nodes (beside the majority maker) of a SUSE Linux Enterprise High Availability Extension 12 cluster. It gathers information about the statuses and configurations of the SAP HANA system replication. It is designed as a normal (stateless) clone resource.

SAP HANA system replication for scale-out is supported in the following scenarios or use cases:

Performance optimized, single container (A > B)

This scenario and setup is described in this document. In the performance optimized scenario an SAP HANA RDBMS on site "A" is synchronizing with an SAP HANA RDBMS on a second site "B". As the SAP HANA RDBMS on the second site is configured to preload the tables the takeover time is typically very short.

Performance optimized, multi-tenancy also named MDC (%A > %B)

Multi-tenancy is supported for all of the above scenarios and use cases. This scenario is supported since SAP HANA 1 SPS12. The setup and configuration from a cluster point of view is the same for multi-tenancy and single containers. Thus you can use the above documents for both types of scenarios.

Multi-tenancy is the default installation type for SAP HANA 2.0.

3.4 The Concept of the Performance Optimized Scenario

In case of failure of the primary SAP HANA on site 1 the cluster first tries to start the takeover process. This allows to use the already loaded data at the secondary site. Typically the takeover is much faster than the local restart.

A site is noticed as "down" or "on error", if the LandscapeHostConfiguration status reflects this (return code 1). This happens when worker nodes are going down without any SAP HANA standby nodes left, which could perform a host auto-failover for the worker functionality.

Without any additional intervention the resource agent will wait for the SAP internal HA cluster to repair the situation locally. An additional intervention could be a custom python hook using the SAP provider srServiceStateChanged() available since SAP HANA 2.0 SPS01.

To achieve an automation of this resource handling process, use the SAP HANA resource agents included in the SAPHanaSR-ScaleOut RPM package delivered with SUSE Linux Enterprise Server for SAP Applications.

You can configure the level of automation by setting the parameter AUTOMATED_REGISTER. If automated registration is activated the cluster will also automatically register a former failed primary to get the new secondary.

3.5 Important Prerequisites

Read the SAP Notes and papers first.

The SAPHanaSR-ScaleOut resource agent software package supports scale-out (multiple-box to multiple-box) system replication with the following configurations and parameters:

  • The cluster must include a valid STONITH method.

  • As the STONITH mechanism SBD is recommended.

  • Both sites are either in the same network segment (layer 2) to allow an easy takeover of an IP Address, or you need a technique like overlay IP addresses in virtual private clouds.

  • Technical users and groups, such as <sid>adm are defined locally in the Linux system.

  • Name resolution of the cluster nodes and the virtual IP address should be done locally on all cluster nodes to not depend on DNS services (as it can fail, too).

  • Time synchronization between the cluster nodes using reliable time services like NTP.

  • Both SAP HANA sites have the same SAP Identifier (SID) and instance number.

  • The SAP HANA scale-out system must have only one active master name server per site. It should have up to three master name server candidates (SAP HANA nodes with a configured role 'master<N>').

  • The SAP HANA scale-out system must have only one failover group.

  • The cluster described in this document does not manage any service IP address for a read-enabled secondary site.

  • There is only one SAP HANA system replication like from site "A" to site "B" but no third site "C" (also called multi-tier or multi-target).

  • The setup implements the performance optimized scenario but not the cost optimized scenario.

  • The saphostagent must be running. saphostagent is needed to translate between the system node names and SAP host names used during the installation of SAP HANA.

  • The replication mode should be either 'sync' or 'syncmem'.

  • All SAP HANA instances controlled by the cluster must not be activated via sapinit autostart.

Important
Important

Automated registration of a failed primary after takeover is possible. But as a good starting configuration for projects, it is recommended to switch off the automated registration of a failed primary, therefore the AUTOMATED_REGISTER="false" is the default.

In this case, you need to register a failed primary after a takeover manually. Use SAP tools like hanastudio or hdbnsutil.

  • For optimal automation, AUTOMATED_REGISTER="true" is recommended.

  • Automated start of SAP HANA instances during system boot must be switched off.

  • You need at least SAPHanaSR-ScaleOut version 0.161, SUSE Linux Enterprise Server for SAP Applications 12 SP2 and SAP HANA 1.0 SPS12 (121) or SAP HANA 2.0 SPS 2 for all mentioned setups.

Important
Important

You must implement a valid STONITH method. Without a valid STONITH method, the complete cluster is unsupported and will not work properly.

This setup-guide focuses on the performance optimized setup as it is the only supported scenario at the point of writing this guide.

If you need to implement a different scenario, it is strongly recommended to define a Proof-of-Concept (PoC) with SUSE. This PoC will focus on testing the existing solution in your scenario. The limitation of most of the above items is mostly due to testing limits.

4 Operating System Setup

This section includes information you should consider during the installation of the operating system.

In this document, first SUSE Linux Enterprise Server for SAP Applications is installed and configured. Then the SAP HANA database including the system replication is set up. Finally the automation with the cluster is set up and configured.

4.1 Installing SUSE Linux Enterprise Server for SAP Applications

Multiple installation guides are already existing, with different reasons to set up the server in a certain way. Below it is outlined where this information can be found. In addition, you will find important details you should consider to get a system which is well prepared to deliver SAP HANA.

4.1.1 Install Base Operating System

Depending on your infrastructure and the hardware used, you need to adapt the installation. All supported installation methods and minimum requirement are described in the Deployment Guide (https://www.suse.com/documentation/sles-12/book_sle_deployment/data/book_sle_deployment.html). In case of automated installations you can find further information in the AutoYaST Guide (https://www.suse.com/documentation/sles-12/book_autoyast/data/book_autoyast.html). The major installation guide for SUSE Linux Enterprise Server for SAP Applications to fit all requirements for SAP HANA is described in the SAP notes:

  • 1984787 SUSE LINUX Enterprise Server 12: Installation notes and

  • 2205917 SAP HANA DB: Recommended OS settings for SLES 12 / SLES for SAP Applications 12.

4.1.2 Install Additional Software

SUSE delivers with SUSE Linux Enterprise Server for SAP Applications special resource agents for SAP HANA. With the pattern sap-hana the resource agent for SAP HANA ScaleUP is installed. For the ScaleOut scenario you need a special resource agent. Follow the instructions below on each node if you have installed the systems based on SAP note 1984787. The pattern High Availability summarizes all tools recommended to be installed on all nodes, including the majority maker.

  • remove package: patterns-sap-hana, SAPHanaSR, yast2-sap-ha

  • install package: SAPHanaSR-ScaleOut, SAPHanaSR-ScaleOut-doc

  • install pattern: ha_sles

To do so, for example, use zypper:

Example 1: Uninstall the SAPHanaSR agent for ScaleUP

As user root, type:

zypper remove SAPHanaSR

If the package is installed, you will get an output like this:

Loading repository data...
Reading installed packages...
Resolving package dependencies...

The following 3 packages are going to be REMOVED:
  patterns-sap-hana SAPHanaSR yast2-sap-ha

The following pattern is going to be REMOVED:
  sap-hana

3 packages to remove.
After the operation, 494.2 KiB will be freed.
Continue? [y/n/...? shows all options] (y): y
(1/3) Removing patterns-sap-hana-12.3-6.8.2.x86_64 ..............................[done]
(2/3) Removing yast2-sap-ha-1.0.0-2.5.12.noarch .................................[done]
(3/3) Removing SAPHanaSR-0.152.21-1.1.noarch ....................................[done]
Example 2: Installation of the SAPHanaSR agent for ScaleOut

As user root, type:

zypper in SAPHanaSR-ScaleOut SAPHanaSR-ScaleOut-doc

If the package is not installed yet, you should get an output like the below:

Refreshing service 'Advanced_Systems_Management_Module_12_x86_64'.
Refreshing service 'SUSE_Linux_Enterprise_Server_for_SAP_Applications_12_SP3_x86_64'.
Loading repository data...
Reading installed packages...
Resolving package dependencies...

The following 2 NEW packages are going to be installed:
  SAPHanaSR-ScaleOut SAPHanaSR-ScaleOut-doc

2 new packages to install.
Overall download size: 539.1 KiB. Already cached: 0 B. After the operation, additional 763.1 KiB will be used.
Continue? [y/n/...? shows all options] (y): y
Retrieving package SAPHanaSR-ScaleOut-0.161.1-1.1.noarch                                                                            (1/2),  48.7 KiB (211.8 KiB unpacked)
Retrieving: SAPHanaSR-ScaleOut-0.161.1-1.1.noarch.rpm ....................................[done]
Retrieving package SAPHanaSR-ScaleOut-doc-0.161.1-1.1.noarch                                                                        (2/2), 490.4 KiB (551.3 KiB unpacked)
Retrieving: SAPHanaSR-ScaleOut-doc-0.161.1-1.1.noarch.rpm ................................[done (48.0 KiB/s)]
Checking for file conflicts: .............................................................[done]
(1/2) Installing: SAPHanaSR-ScaleOut-0.161.1-1.1.noarch ..................................[done]
(2/2) Installing: SAPHanaSR-ScaleOut-doc-0.161.1-1.1.noarch ..............................[done]

Install the tools for High Availability on all nodes.

zypper in --type pattern ha_sles

4.1.3 Get latest Updates

If you have installed the packages before, make sure to deploy the newest updates on all machines to have the latest versions of the resource agents and other packages. A prerequisite is a valid subscription for SUSE Linux Enterprise Server for SAP Applications. There are multiple ways to get updates via SUSE Manager, the Subscription Management Tool (SMT), or via a direct connection to the SUSE Customer Center (SCC).

Depending on your company or customer rules, use zypper update or zypper patch.

Example 3: Software update must be triggered from each node

zypper patch will install all available needed patches. As user root, type:

zypper patch

zypper update will update all or specified installed packages with newer versions, if possible. As user root, type:

zypper update

4.2 Configure SUSE Linux Enterprise Server for SAP Applications to Run SAP HANA

4.2.1 Tuning / Modification

Operating system tuning are described in SAP note 1275776 and 2205917. The SAP note 1275776 explains three ways to implementing the settings.

Example 4: Using saptune (preferred)
saptune solution apply HANA
Example 5: Using sapconf
tuned-adm profile sap-hana

The SAP note 2205917 covers the following modifications:

  • SUSE Linux Enterprise Server 12 GA (no SP) and SUSE Linux Enterprise Server 12 SP1 Linux kernel upgrade

  • SUSE Linux Enterprise Server 12 SP2 Linux kernel upgrade

  • SUSE Linux Enterprise Server 12 SP3 Linux kernel upgrade

  • Additional 3rd-party kernel modules

  • Configure tuned to use profile "sap-hana" (applies to Intel-based systems only)

  • Turn off NUMA balancing

  • Disable transparent hugepages

  • Configure C-States for lower latency in Linux (applies to Intel-based systems only)

  • CPU Frequency/Voltage scaling (applies to Intel-based systems only)

  • Energy Performance Bias (EPB, applies to Intel-based systems only)

  • Turn off kernel samepage merging (KSM)

  • Linux pagecache limit

4.2.2 Enable SSH Access via Public Key (optional)

Public key authentication provides SSH users access to their servers without entering their passwords. SSH keys are also more secure than passwords, because the private key used to secure the connection is never shared. Private keys can also be encrypted. Their encrypted contents cannot easily be read. For the document at hand, a very simple but useful setup is used. This setup is based on only one ssh-key pair which enables SSH access to all cluster nodes.

Note
Note

Follow your company security policy to set up access to the systems.

Example 6: SSH key creation and exchange

As user root create an SSH key on one node.

ssh-keygen -t rsa

The ssh-key generation asks for missing parameters.

Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:ip/8kdTbYZNuuEUAdsaYOAErkwnkAPBR7d2SQIpIZCU root@<host1>
The key's randomart image is:
+---[RSA 2048]----+
|XEooo+ooo+o      |
|=+.= o=.o+.      |
|..B o. + o.      |
|   o  . +... .   |
|        S.. *    |
|     . o . B o   |
|    . . o o =    |
|     o . . +     |
|      +.. .      |
+----[SHA256]-----+

After the ssh-keygeer, the ssh-keygen is set up; you will have two new files under /root/.ssh/ .

ls /root/.ssh/
id_rsa  id_rsa.pub

Collect the public host keys from all other node. For the document at hand, the ssh-keyscan command is used.

ssh-keyscan

The SSH host key is automatically collected and stored in the file /root/.ssh/known_host during the first SSH connection. To avoid to confirm the first login with "yes", which accepts the host key, collect and store them beforehand.

ssh-keyscan -t ecdsa-sha2-nistp256 <host1>,<host1 ip> >>.ssh/known_hosts
ssh-keyscan -t ecdsa-sha2-nistp256 <host2>,<host2 ip> >>.ssh/known_hosts
ssh-keyscan -t ecdsa-sha2-nistp256 <host3>,<host3 ip> >>.ssh/known_hosts
...

After collecting all host keys, store them in a file named authorized_keys. Push the complete directory /root/.ssh/ from the first node to all further cluster members.

rsync -ay /root/.ssh/ <host2>:/root/.ssh/
rsync -ay /root/.ssh/ <host3>:/root/.ssh/
rsync -ay /root/.ssh/ <host4>:/root/.ssh/
....

4.2.3 Set up Disk Layout for SAP HANA

An SAP certified storage system with a validated storage API is generally recommended. This is a prerequisite of a stable and reliable scale-out installation.

  • /hana/shared/<SID>

  • /hana/data/<SID>

  • /hana/log/<SID>

Create the mount directories on all SAP HANA nodes.

mkdir -p /hana/shared/<SID>
mkdir -p /hana/data/<SID>
mkdir -p /hana/log/<SID>
mkdir -p /usr/sap

The SAP HANA installation needs a special storage setup. The NFS setup used for this guide must be reboot-persistent. You can achieve this with entries in the /etc/fstab .

Note
Note

NFS version 4 is required in the setup at hand.

Example 7: Create permanent mount entries for all NFS pools

Create /etc/fstab entries for the three NFS pools.

<nfs1>  /hana/data/<SID>      nfs4  defaults  0 0
<nfs2>  /hana/shared/<SID>    nfs4  defaults  0 0
<nfs3> /hana/log/<SID>        nfs4  defaults  0 0

In the sample environment those lines are as follows:

/exports/{SID}_WDF1/shared  /hana/data/HA1      nfs4  defaults  0 0
/exports/{SID}_WDF1/data  /hana/shared/HA1    nfs4  defaults  0 0
/exports/{SID}_WDF1/log /hana/log/HA1        nfs4  defaults  0 0

Mount all NFS shares.

mount -a

Create other directories (optional).

mkdir -p /sapsoftware

File systems

/hana/shared/<SID>

The mount directory is used for shared files between all hosts in an SAP HANA system. This directory needs to be accessible to each of the servers in the SAP HANA cluster.

/hana/log/<SID>

The default path to the log directory depends on the system ID of the SAP HANA host.

/hana/data/<SID>

The default path to the data directory depends on the system ID of the SAP HANA host.

/usr/sap

This is the path to the local SAP system instance directories. It is possible to join this location with the Linux installation.

/sapsoftware

(optional) Space for copying the SAP install software media. This NFS pool is mounted on both sites and contains the SAP HANA installation media and installation parameter files.

Set up host name resolution for all machines.

You can either use a DNS server or modify the /etc/hosts on all nodes.

With maintaining the /etc/hosts file, you minimize the impact of a failing DNS service. Replace the IP address and the host name in the following commands.

vi /etc/hosts

Insert the following lines to /etc/hosts. Change the IP address and host name to match your environment.

192.168.201.151 suse01
192.168.201.152 suse02
...

Enable NTP service on all nodes.

Simply enable an ntp service on all node in the cluster to have proper time synchronization.

yast2 ntp-client

5 Installing the SAP HANA Databases on Both Sites

The infrastructure is set up. Now install the SAP HANA database on both sites. In a cluster a machine is also called a node.

In the example at hand, to make it easier to follow the documentation, the machines (or nodes) are named suse01, …​ suseXX. The nodes with odd numbers (suse01, suse03, suse05, …​) will be part of site "A" (WDF1) and the nodes with even numbers (suse02, suse04, suse06, …​) will be part of site "B"(ROT1) .

The following users are automatically created during the SAP HANA installation:

<sid>adm

The user<sid>adm is the operating system user required for administrative tasks, such as starting and stopping the system.

sapadm

The SAP Host Agent administrator.

SYSTEM

The SAP HANA database superuser.

5.1 Preparation

  • Read the SAP Installation and Setup Manuals available at the SAP Marketplace.

  • Download the SAP HANA Software from SAP Marketplace.

  • Mount the file systems to install SAP HANA database software and database content (data and log).

5.2 Installation

  1. Mount /hana/shared from the nfs server.

    for system in suse0{1,2,3,4,5,6}; do
        ssh $system mount -a
    done
  2. Install the SAP HANA Database as described in the SAP HANA Server Installation Guide on all machines (two sites) except the majority maker. Both databases need to have same SID and instance number. You can use either the graphical user interface or the command line installer hdblcm. The command line installer can be used in an interactive or batch mode.

    Example 8: Using hdblcm in interactive mode
    # <path_to_sap_media>/hdblcm

    Alternatively you can also use the batch mode of hdblcm. This can either be done by specifying all needed parameters via the command line or by using a parameter file.

    In the example at hand the command line parameters are used. In the batch mode you need to provide an XML password file (here <path>/hana_passwords). A template of this password file can be created with the following command:

    Example 9: Creating a password file
    <path_to_sap_media>/hdblcm --dump_configfile_template=templateFile

    This command creates two files:

    • templateFile is the template for a parameter file.

    • templateFile.xml is the XML template used to provide several hana_passwords to the hdblcm installer.

    The XML password file looks as follows:

    Example 10: The XML password template
    <?xml version="1.0" encoding="UTF-8"?>
    <!-- Replace the 3 asterisks with the password -->
    <Passwords>
        <root_password><![CDATA[***]]></root_password>
        <sapadm_password><![CDATA[***]]></sapadm_password>
        <master_password><![CDATA[***]]></master_password>
        <sapadm_password><![CDATA[***]]></sapadm_password>
        <password><![CDATA[***]]></password>
        <system_user_password><![CDATA[***]]></system_user_password>
        <streaming_cluster_manager_password><![CDATA[***]]></streaming_cluster_manager_password>
        <ase_user_password><![CDATA[***]]></ase_user_password>
        <org_manager_password><![CDATA[***]]></org_manager_password>
    </Passwords>

    After having created the XML password file, you can immediately start the SAP HANA installation in batch mode by providing all needed parameters via the command line.

    Example 11: Using hdblcm in batch mode
    # cat <path>/hana_passwords | \
    <path_to_sap_media>/hdblcm \
      --batch \
      --sid=<SID>\
      --number=<Inst> \
      --action=install \
      --hostname=<node1> \
      --addhosts=<node2>:role=worker,<node3>:role=standby  \
      --certificates_hostmap=<node1>=<node1> \
      --certificates_hostmap=<node2>=<node2> \
      --certificates_hostmap=<node3>=<node3> \
      --install_hostagent \
      --system_usage=test \
      --sapmnt=/hana/shared \
      --datapath=<datapath> \
      --logpath=<logpath> \
      --root_user=root  \
      --workergroup=default \
      --home=/usr/sap/<SID>/home \
      --userid=<uid> \
      --shell=/bin/bash \
      --groupid=<gid> \
      --read_password_from_stdin=xml

5.3 Checks

Verify that both database sites are up and all processes of these databases are running correctly.

  1. As Linux user <sid>adm use the SAP command line tool HDB to get an overview of all running SAP HANA processes. The output of HDB info should look like the example below for both sites:

    Example 12: Calling HDB info (as user <sid>adm)
    HDB info

    The HDB info command lists the processes currently running for that SID.

    USER           PID  ...  COMMAND
    ha1adm         6561 ...  -csh
    ha1adm         6635 ...    \_ /bin/sh /usr/sap/HA1/HDB00/HDB info
    ha1adm         6658 ...        \_ ps fx -U HA1 -o user,pid,ppid,pcpu,vsz,rss,args
    ha1adm         5442 ...  sapstart pf=/hana/shared/HA1/profile/HA1_HDB00_suse01
    ha1adm         5456 ...   \_ /usr/sap/HA1/HDB00/suse01/trace/hdb.sapha1_HDB00 -d -nw -f /usr/sap/ha1/HDB00/suse
    ha1adm         5482 ...       \_ hdbnameserver
    ha1adm         5551 ...       \_ hdbpreprocessor
    ha1adm         5554 ...       \_ hdbcompileserver
    ha1adm         5583 ...       \_ hdbindexserver
    ha1adm         5586 ...       \_ hdbstatisticsserver
    ha1adm         5589 ...       \_ hdbxsengine
    ha1adm         5944 ...       \_ sapwebdisp_hdb pf=/usr/sap/HA1/HDB00}/suse01/wdisp/sapwebdisp.pfl -f /usr/sap/SL
    ha1adm         5363 ...  /usr/sap/HA1/HDB00/exe/sapstartsrv pf=/hana/shared/HA1/profile/HA1_HDB00_suse02 -D -u s
  2. Use the python script landscapeHostConfiguration.py to show the status of an entire SAP HANA site.

    Example 13: Query the host roles (as user <sid>adm)
    HDBSettings.sh landscapeHostConfiguration.py

    The landscape host configuration is shown with a line per SAP HANA host.

     | Host   | Host   |... NameServer  | NameServer  | IndexServer | IndexServer
     |        | Active |... Config Role | Actual Role | Config Role | Actual Role
     | ------ | ------ |... ----------- | ----------- | ----------- | -----------
     | suse01 | yes    |... master 1    | master      | worker      | master
     | suse03 | yes    |... master 2    | slave       | worker      | slave
     | suse05 | yes    |... master 3    | slave       | standby     | standby
    
     overall host status: ok
  3. Get an overview of instances of that site (as user <sid>adm)

    Example 14: Get the list of instances
    sapcontrol -nr <Inst> -function GetSystemInstanceList

    You should get a list of SAP HANA instances belonging to that site.

    12.06.2018 17:25:16
    GetSystemInstanceList
    OK
    hostname, instanceNr, httpPort, httpsPort, startPriority, features, dispstatus
    suse01, 00, 50013, 50014, 0.3, HDB|HDB_WORKER, GREEN
    suse05, 00, 50013, 50014, 0.3, HDB|HDB_WORKER, GREEN
    suse03, 00, 50013, 50014, 0.3, HDB|HDB_WORKER, GREEN

6 Set up the SAP HANA System Replication

This section describes the setup of the system replication (HSR) after SAP HANA has been installed properly.

Procedure

  1. Back up the primary database

  2. Enable the primary database

  3. Register the secondary database

  4. Verify the system replication

For more information read the Section Setting Up System Replication of the SAP HANA Administration Guide.

6.1 Back Up the Primary Database

First back up the primary database as described in the SAP HANA Administration Guide, Section SAP HANA Database Backup and Recovery.

Below find examples to back up SAP HANA with SQL Commands:

Example 15: Simple backup for the system database and all tenants with one singe backup call

As user <sid>adm enter the following command:

hdbsql -u SYSTEM -d SYSTEMDB \
   "BACKUP DATA FOR FULL SYSTEM USING FILE ('backup')"

You get the following command output (or similar):

0 rows affected (overall time 15.352069 sec; server time 15.347745 sec)
Example 16: Simple backup for a single container (non MDC) database

Enter the following command as user <sid>adm:

hdbsql -i <Inst> -u <dbuser> \
   "BACKUP DATA USING FILE ('backup')"
Important
Important

Without a valid backup, you cannot bring SAP HANA into a system replication configuration.

6.2 Enable Primary Database

As Linux user <sid>adm enable the system replication at the primary node. You need to define a site name (like WDF1) which must be unique for all SAP HANA databases which are connected via system replication. This means the secondary must have a different site name.

Example 17: Enable the system replication on the primary site

As user <sid>adm enable the primary:

hdbnsutil -sr_enable --name=WDF1

Check if the command output is similar to:

nameserver is active, proceeding ...
successfully enabled system as system replication source site
done.

The command line tool hdbnsutil can be used to check the system replication mode and site name.

Example 18: Check the system replication configuration status as user <sid>adm on the primary
hdbnsutil -sr_stateConfiguration

If the system replication enablement was successful at the primary, the output should be as follows:

checking for active or inactive nameserver ...
System Replication State
~~~~~~~~~~~~~~~~~~~~~~~~

mode: primary
site id: 1
site name: WDF1
done.

The mode has changed from “none” to “primary” and the site now has a site name and a site ID.

6.3 Register the Secondary Database

The SAP HANA database instance on the secondary side must be stopped before the system can be registered for the system replication. You can use your preferred method to stop the instance (like HDB or sapcontrol). After the database instance has been stopped successfully, you can register the instance using hdbnsutil.

Example 19: Stop the secondary as Linux user <sid>adm:
sapcontrol -nr <Inst> -function StopSystem
Example 20: Copy the KEY and KEY-DATA file from the primary to the secondary site

The copy of key and key-data should only be done on the master name server. As the files are in the global file space, you do not need to run the command on all cluster nodes.

cd /usr/sap/<SID>/SYS/global/security/rsecssfs
rsync -va {,<node1-siteB>:}$PWD/data/SSFS_<SID>.DAT
rsync -va {,<node1-siteB>:}$PWD/key/SSFS_<SID>.KEY
Example 21: Register the secondary as Linux user <sid>adm:
hdbnsutil -sr_register --name=<site2> \
     --remoteHost=<node1-siteA> --remoteInstance=<Inst> \
     --replicationMode=sync --operationMode=logreplay
adding site ...
checking for inactive nameserver ...
nameserver suse02:30001 not responding.
collecting information ...
updating local ini files ...
done.

The remoteHost is the primary node in our case, the remoteInstance is the database instance number (here 00).

Now start the database instance again and verify the system replication status. On the secondary site, the mode should be one of „SYNC“, „SYNCMEM“ or „ASYNC“. The mode depends on the sync option defined during the registration of the secondary.

Example 22: Start the system on the secondary site as user <sid>adm
sapcontrol -nr <Inst> -function StartSystem

Wait until the SAP HANA database is started completely.

Example 23: Check the system replication configuration as Linux user <sid>adm
hdbnsutil -sr_stateConfiguration

The output should look like the following:

System Replication State
~~~~~~~~~~~~~~~~~~~~~~~~
mode: sync
site id: 2
site name: ROT1
active primary site: 1

primary masters: suse01 suse03 suse05
done.

6.4 Verify the System Replication

To view the replication state of the whole SAP HANA cluster, use the following command as <sid>adm user on the primary site.

Example 24: Check the system replication status at the primary site (as <sid>adm)
HDBSettings.sh systemReplicationStatus.py

This script prints a human-readable table of the system replication channels and their status. The most interesting column is the Replication Status, which should be ACTIVE.

| Database | Host   | .. Site Name | Secondary | .. Secondary | .. Replication
|          |        | ..           | Host      | .. Site Name | .. Status
| -------- | ------ | .. --------- | --------- | .. --------- | .. ------
| SYSTEMDB | suse01 | .. WDF1      | suse02    | .. ROT1      | .. ACTIVE
| HA1      | suse01 | .. WDF1      | suse02    | .. ROT1      | .. ACTIVE
| HA1      | suse01 | .. WDF1      | suse02    | .. ROT1      | .. ACTIVE
| HA1      | suse03 | .. WDF1      | suse04    | .. ROT1      | .. ACTIVE

status system replication site "2": ACTIVE
overall system replication status: ACTIVE

Local System Rm Replication State
~~~~~~~~~~

mode: PRIMARY
site id: 1
site name: WDF1

7 Integration of SAP HANA with the Cluster

Proceed with the following steps:

Procedure

  1. Implement the python hook SAPHanaSR

  2. Configure system replication operation mode

  3. Allow <sid>adm to access the cluster

  4. Start SAP HANA

  5. Test the hook integration

7.1 Implement the Python Hook SAPHanaSR

This step must be done on both sites. SAP HANA must be stopped to change the global.ini and allow SAP HANA to integrate the HA/DR hook script during start.

  • Install the HA/DR hook script into a read/writable directory

  • Integrate the hook into global.ini (SAP HANA needs to be stopped for doing that offline)

  • Check integration of the hook during start-up

Take the hook from the SAPHanaSR-scaleOut package and copy it to your preferred directory like /hana/share/myHooks. The hook must be available on all SAP HANA nodes.

suse01~ # mkdir -p /hana/shared/myHooks
suse01~ # cp /usr/share/SAPHanaSR-ScaleOut/SAPHanaSR.py /hana/shared/myHooks
suse01~ # chown -R <sid>adm:sapsys /hana/shared/myHooks

Stop SAP HANA.

sapcontrol -nr <Inst> -function StopSystem
Example 25: Adding SAPHanaSR via global.ini
[ha_dr_provider_SAPHanaSR]
provider = SAPHanaSR
path = /hana/shared/myHooks
execution_order = 1

[trace]
ha_dr_saphanasr = info

7.2 Configure System Replication Operation Mode

When your system is connected as an SAPHanaSR target, you can find an entry in the global.ini file which defines the operation mode. Up to now there are two modes available:

  • delta_datashipping

  • logreplay

Until performing a takeover and re-registration in the opposite direction, the entry for the operation mode is missing on your primary site. The "classic" operation mode is delta_datashipping. The preferred mode for HA is logreplay. Using the operation mode logreplay makes your secondary site in the SAP HANA system replication a hot standby system. For more details regarding both modes check the SAP documentation such as "How To Perform System Replication for SAP HANA" (see https://www.sap.com/documents/2013/10/26c02b58-5a7c-0010-82c7-eda71af511fa.html).

Check both global.ini files and add the operation mode, if needed.

section

[ system_replication ]

key

operation_mode = logreplay

Path for the global.ini: /hana/shared/<SID>/global/hdb/custom/config/

[system_replication]
operation_mode = logreplay

7.3 Allow <sid>adm to Access the Cluster

The current version of the SAPHanaSR python hook uses the command sudo to allow the <sid>adm user to access the cluster attributes. In Linux you can use visudo to start the vi editor for the /etc/sudoers configuration file.

The user <sid>adm must be able to set the cluster attribute hana_<sid>_glob_srHook. The SAP HANA system replication hook needs password free access. The following example limits the sudo access to exactly setting the needed attribute.

Replace the <sid> by the lowercase SAP system ID.

Example 26: Entry in sudo permissions /etc/sudoers file

Basic parameter option to allow <sidadm> to use the srHook.

# SAPHanaSR-ScaleOut needs for srHook
<sid>adm ALL=(ALL) NOPASSWD: /usr/sbin/crm_attribute -n hana_<sid>_glob_srHook -v *

More specific parameters option to meet a high security level.

# SAPHanaSR-ScaleOut needs for srHook
Cmnd_Alias SOK   = /usr/sbin/crm_attribute -n hana_<sid>_glob_srHook -v SOK   -t crm_config -s SAPHanaSR
Cmnd_Alias SFAIL = /usr/sbin/crm_attribute -n hana_<sid>_glob_srHook -v SFAIL -t crm_config -s SAPHanaSR
<sid>adm ALL=(ALL) NOPASSWD: SOK, SFAIL
Example 27: Result of replacg <sid> wLC} with ha1
# SAPHanaSR-ScaleOut needs for srHook
ha1adm ALL=(ALL) NOPASSWD: /usr/sbin/crm_attribute -n hana_ha1_glob_srHook -v *

7.4 Start SAP HANA

After having completed the SAP HANA integration and having configured the communication between SAP HANA and the cluster, you can start the SAP HANA databases on both sites.

Example 28: Starting a complete SAP HANA site as use <sid>adm
sapcontrol -nr <Inst> -function StartSystem

The sapcontrol service commits the request with OK.

11.06.2018 18:30:16
StartSystem
OK

Check if SAP HANA has finished starting.

sapcontrol -nr <Inst> -function WaitforStarted 300 20

7.5 Test the Hook Integration

When the SAP HANA database has been restarted after the changes, check if the hook script is called correctly.

First check if SAP HANA did create a compiled version of the python script. The file list in /hana/shared/myHooks should now also contain a file with extention pyc.

cd /hana/shared/myHooks; ll
-rw-r--r-- 1 <sid>adm sapsys 4890 May  4 14:40 SAPHanaSR.py
-rw-r--r-- 1 <sid>adm sapsys 4932 Jun 11 15:00 SAPHanaSR.pyc

A second verification is to check the SAP HANA trace files as <sid>adm:

suse01:ha1adm> cdtrace
suse01:ha1adm> awk  '/ha_dr_SAPHanaSR.*crm_attribute/ \
     { printf "%s %s %s %s\n",$2,$3,$5,$16 }' nameserver_suse01.*
2018-05-04 12:34:04.476445 ha_dr_SAPHanaSR SFAIL
2018-05-04 12:53:06.316973 ha_dr_SAPHanaSR SOK

8 Configuration of the Cluster and SAP HANA Resources

This chapter describes the configuration of the SUSE Linux Enterprise High Availability cluster. The SUSE Linux Enterprise High Availability Extension is part of SUSE Linux Enterprise Server for SAP Applications. Further, the integration of SAP HANA System Replication with the SUSE Linux Enterprise High Availability cluster is explained. The integration is done by using the SAPHanaSR-ScaleOut package which is also part of SUSE Linux Enterprise Server for SAP Applications.

Procedure

  1. Installation of cluster packages

  2. Basic Cluster Configuration

  3. Configure Cluster Properties and Resources

  4. Final steps

8.1 Installation of Cluster Packages

If not already done, install the pattern High Availability on all nodes.

To do so, use zypper.

zypper in -t pattern ha_sles

Now the Resource Agents for controlling the SAP HANA system replication need to be installed at all cluster nodes, including the majority maker.

zypper in SAPHanaSR-scaleOut

If you have the packages installed before, make sure to get the newest updates on all nodes

zypper patch

8.2 Basic Cluster Configuration

After having installed the cluster packages, the next step is to set up the basic cluster framework. For convenience, use YaST or the ha-cluster-init script.

Important
Important

It is strongly recommended to add a second corosync ring, implement unicast (UCAST) communication and adjust the timeout values to your environment.

Prerequisites

  • Name resolution

  • Time sychronisation

  • Redundant network for cluster intercommunication

  • STONITH method

8.2.1 Set up Watchdog for "Storage-based Fencing"

It is recommended to use SBD as central stonith device, as done in the example at hand. Each node constantly monitors connectivity to the storage device, and terminates itself in case the partition becomes unreachable. Whenever SBD is used, a correctly working watchdog is crucial. Modern systems support a hardware watchdog that needs to be "tickled" or "fed" by a software component. The software component (usually a daemon) regularly writes a service pulse to the watchdog. If the daemon stops feeding the watchdog, the hardware will enforce a system restart. This protects against failures of the SBD process itself, such as dying, or getting stuck on an I/O error.

Example 29: Set up for Watchdog
Important
Important

Access to the Watchdog Timer: No other software must access the watchdog timer. Some hardware vendors ship systems management software that uses the watchdog for system resets (for example, HP ASR daemon). Disable such software, if watchdog is used by SBD.

Determine the right watchdog module. Alternatively, you can find a list of installed drivers with your kernel version.

ls -l /lib/modules/$(uname -r)/kernel/drivers/watchdog

Check if any watchdog module is already loaded.

lsmod | egrep "(wd|dog|i6|iT|ibm)"

If you get a result, the system has already a loaded watchdog. If the watchdog does not match your watchdog device, you need to unload the module.

To safely unload the module, check first if an application is using the watchdog device.

lsof /dev/watchdog
rmmod <wrong_module>

Enable your watchdog module and make it persistent. For the example below, softdog has been used which has some restrictions and should not be used as first option.

echo softdog > /etc/modules-load.d/watchdog.conf
systemctl restart systemd-modules-load

Check if the watchdog module is loaded correctly.

lsmod | grep dog

Testing the watchdog can be done with a simple action. Ensure to switch of your SAP HANA first because watchdog will force an unclean reset / shutdown of your system.

In case of a hardware watchdog a desired action is predefined after the timeout of the watchdog has reached. If your watchdog module is loaded and not controlled by any other application, do the following:

Important
Important

Trigger the watchdog without continuously updating the watchdog does reset/switchoff the system. This is the intended mechanism. The following commands will force your system to be reset/switched off.

touch /dev/watchdog

In case the softdog module is used the following action can be performed:

echo 1> /dev/watchdog

After your test was successful you can implement the watchdog on all cluster members. The example below applies to the softdog module. Replace <wrong_module> by the module name queried before.

for i in suse{02,03,04,05,06,-mm}; do
    ssh -T $i <<EOSSH
        hostname
        rmmod <wrong_module>
        echo softdog > /etc/modules-load.d/watchdog.conf
        systemctl restart systemd-modules-load
        lsmod |grep -e dog
EOSSH
done

8.2.2 Initial Cluster Setup Using ha-cluster-init

For more detailed information about ha-cluster-* tools, see section Overview of the Bootstrap Scripts in https://www.suse.com/documentation/sle_ha/

Create an initial setup by using ha-cluster-init command. Follow the dialog steps.

Note
Note

This is only to be done on the first cluster node. If you are using SBD as STONITH mechanism, you need to first load the watchdog kernel module matching your setup. In the example at hand the softdog kernel module is used.

The command ha_cluster-init configures the basic cluster framework including:

  • SSH keys

  • csync2 to transfer configuration files

  • SBD (at least one device)

  • corosync (at least one ring)

  • HAWK Web interface

ha-cluster-init -u -s <sbd-device>

As requested by ha-cluster-init, change the password of the user hacluster on all cluster nodes.

Note
Note

Do not forget to change the password of the user hacluster.

8.2.3 Cluster Configuration for All Other Cluster Nodes

The other nodes of the cluster could be integrated by starting the command ha-cluster-join. This command asks for the IP address or name of the first cluster node. Than all needed configuration files are copied over. As a result the cluster is started on all nodes. Do not forget the majority maker.

If you are using SBD as STONITH method, you need to activate the softdog kernel module matching your systems. In the example at hand the softdog kernel module is used.

ha-cluster-join -c <host1>

8.2.4 Check the Cluster for the First Time

Now it is time to check and optionally start the cluster for the first time on all nodes.

Note
Note

All nodes should be started in parallel. Otherwise unseen nodes might get fenced.

Check the cluster status with crm_mon. Use the option -r to also see resources which are configured but stopped.

crm_mon -r

The command will show the "empty" cluster and will print something like the screen output below. The most interesting information in this output is that there are two nodes in the status "online" and the message "partition with quorum".

Stack: corosync
Current DC: suse05 (version 1.1.16-4.8-77ea74d) - partition with quorum
Last updated: Mon Jun 11 16:55:04 2018
Last change: Mon Jun 11 16:53:58 2018 by root via crm_attribute on suse02

7 nodes configured
1 resource configured

Online: [ suse-mm suse01 suse02 suse03 suse04 suse05 suse06 ]

Full list of resources:

stonith-sbd     (stonith:external/sbd): Started suse-mm

8.3 Configure Cluster Properties and Resources

This section describes how to configure bootstrap, STONITH, resources, and constraints using the crm configure shell command as described in section Configuring and Managing Cluster Resources (Command Line) of the SUSE Linux Enterprise High Availability Administration Guide (see https://www.suse.com/documentation/sle-ha-12/singlehtml/book_sleha/book_sleha.html#cha.ha.manual_config).

Use the command crm to add the objects to the Cluster Resource Management (CRM). Copy the following examples to a local file and then load the configuration to the Cluster Information Base (CIB). The benefit is that you have a scripted setup and a backup of your configuration.

Perform all crm commands only on one node, for example on machine suse01.

First write a text file with the configuration, which you load into your cluster in a second step. This step is as follows:

vi crm-file<XX>
crm configure load update crm-file<XX>

8.3.1 Cluster Bootstrap and more

The first example defines the cluster bootstrap options including the resource and operation defaults.

The stonith-timeout should be greater than 1.2 times the SBD msgwait timeout.

vi crm-bs.txt

Enter the following to crm-bs.txt:

property $id="cib-bootstrap-options" \
              no-quorum-policy="freeze" \
              stonith-enabled="true" \
              stonith-action="reboot" \
              stonith-timeout="150s"
              rsc_defaults $id="rsc-options" \
              resource-stickiness="1000" \
              migration-threshold="5"
op_defaults $id="op-options" \
              timeout="600"

Now add the configuration to the cluster.

crm configure load update crm-bs.txt

8.3.2 STONITH

As already explained in the requirements, STONITH is crucial for a supported cluster setup. Without a valid fencing mechanism your cluster is unsupported.

A standard STONITH mechanism implements SBD based fencing. The SBD STONITH method is very stable and reliable and has proved very good road capability.

You can use other fencing methods available for example from your public cloud provider. However, it is crucial to intensively test the server fencing.

For SBD based fencing you can use one up to three SBD devices. The cluster will react differently when an SBD device is lost. The differences and SBD fencing are explained very well in the SUSE product documentation of the SUSE Linux Enterprise High Availability Extension available at https://www.suse.com/documentation/.

You need to adapt the SBD resource for the SAP HANA scale-out cluster.

As user <sid>adm create a file named for g.txt.

Example 30: Configure fencing
vi crm-fencing.txt

Enter the following to crm-fencing.txt:

primitive stonith-sbd stonith:external/sbd \
        params pcmk_action_limit=-1 pcmk_delay_max=30s

Now load the configuration from the file to the cluster.

crm configure load update crm-fencing.txt

8.3.3 Cluster in Maintenance Mode

Load the configuration for the resources and the constraints step-by-step to the cluster to explain the different parts. The best way to avoid unexpected cluster reactions is to

  • first set the complete cluster to maintenance mode,

  • then do all needed changes and,

  • as last step, end the cluster maintenance mode.

crm configure property maintenance-mode=true

8.3.4 SAPHanaTopology

Next, define the group of resources needed, before the SAP HANA instances can be started. Prepare the changes in a text file, for example crm-saphanatop.txt, and load these with the crm command.

You need to potentially change the SID and instance number (bold) to your values.

Example 31: Configure SAPHanaTopology
suse01:~ # vi crm-saphanatop.txt

Enter the following to crm-saphanatop.txt:

primitive rsc_SAPHanaTop_<SID>_HDB<Inst> ocf:suse:SAPHanaTopology \
        op monitor interval="10" timeout="600" \
        op start interval="0" timeout="600" \
        op stop interval="0" timeout="300" \
        params SID="<SID>" InstanceNumber="<Inst>"

clone cln_SAPHanaTop_<SID>_HDB<Inst> rsc_SAPHanaTop_<SID>_HDB<Inst> \
        meta clone-node-max="1" interleave="true"
primitive rsc_SAPHanaTop_HA1_HDB00 ocf:suse:SAPHanaTopology \
        op monitor interval="10" timeout="600" \
        op start interval="0" timeout="600" \
        op stop interval="0" timeout="300" \
        params SID="HA1" InstanceNumber="00"

clone cln_SAPHanaTop_HA1_HDB00 rsc_SAPHanaTop_HA1_HDB00 \
        meta clone-node-max="1" interleave="true"

Additional information about all parameters can be found with the command man ocf_suse_SAPHanaTopology.

Again, add the configuration to the cluster.

crm configure load update crm-saphanatop.txt

The most important parameters here are SID (HA1) and InstanceNumber (00), which are self explaining in an SAP context.

Beside these parameters, the timeout values or the operations (start, monitor, stop) are typical values to be adjusted for your environment.

8.3.5 SAPHanaController

Next, define the group of resources needed, before the SAP HANA instances can be started. Edit the changes in a text file, for example crm-saphanacon.txt and load these with the command crm.

vi crm-saphanacon.txt
Example 32: Configure SAPHanaController

Enter the following to crm-saphanacon.txt

primitive rsc_SAPHanaCon_<SID>_HDB<Inst> ocf:suse:SAPHanaController \
        op start interval="0" timeout="3600" \
        op stop interval="0" timeout="3600" \
        op promote interval="0" timeout="3600" \
        op monitor interval="60" role="Master" timeout="700" \
        op monitor interval="61" role="Slave" timeout="700" \
        params SID="<SID>" InstanceNumber="<Inst>" \
        PREFER_SITE_TAKEOVER="true" \
        DUPLICATE_PRIMARY_TIMEOUT="7200" AUTOMATED_REGISTER="false"

ms msl_SAPHanaCon_<SID>_HDB<Inst> rsc_SAPHanaCon_<SID>_HDB<Inst> \
        meta clone-node-max="1" master-max="1" interleave="true"

The most important parameters here are <SID> (HA1) and <Inst> (00), which are in the SAP context quite self explaining. Beside these parameters, the timeout values or the operations (start, monitor, stop) are typical tuneables.

primitive rsc_SAPHanaCon_HA1_HDB00 ocf:suse:SAPHanaController \
        op start interval="0" timeout="3600" \
        op stop interval="0" timeout="3600" \
        op promote interval="0" timeout="3600" \
        op monitor interval="60" role="Master" timeout="700" \
        op monitor interval="61" role="Slave" timeout="700" \
        params SID="HA1" InstanceNumber="00" PREFER_SITE_TAKEOVER="true" \
        DUPLICATE_PRIMARY_TIMEOUT="7200" AUTOMATED_REGISTER="false"

ms msl_SAPHanaCon_HA1_HDB00 rsc_SAPHanaCon_HA1_HDB00 \
        meta clone-node-max="1" master-max="1" interleave="true"

Add the configuration to the cluster.

crm configure load update crm-saphanacon.txt
Table 2: Table Description of important Resource Agent parameter
NameDescription

PREFER_SITE_TAKEOVER

Defines whether RA should prefere to takeover to the seconadry instance instead of restarting the failed primary locally.

AUTOMATED_REGISTER

Defines whether a former primary should be automatically registered to be secondary of the new primary. With this parameter you can adapt the level of system replication automation.

If set to false, the former primary must be manually registered. The cluster will not start this SAP HANA RDBMS until it is registered to avoid double primary up situations.

DUPLICATE_PRIMARY_TIMEOUT

Time difference needed between two primary time stamps if a dual-primary situation occurs. If the time difference is less than the time gap, the cluster holds one or both sites in a "WAITING" status. This is to give an administrator the chance to react on a failover. If the complete node of the former primary crashed, the former primary will be registered after the time difference is passed. If "only" the SAP HANA RDBMS has crashed, then the former primary will be registered immediately. After this registration to the new primary, all data will be overwritten by the system replication.

Additional information about all parameters can be found with the command man ocf_suse_SAPHana_Controller.

8.3.6 The virtual IP Address

The last resource to be added to the cluster is covering the virtual IP address. Replace the bold string with your instance number, SAP HANA system ID and the virtual IP address.

Example 33: Configure the IP Address
vi crm-vip.txt

Enter the following to crm-vip.txt:

primitive rsc_ip_<SID>_HDB<Inst> ocf:heartbeat:IPaddr2 \
        op monitor interval="10s" timeout="20s" \
        params ip="<IP>"
primitive rsc_ip_HA1_HDB00 ocf:heartbeat:IPaddr2 \
        op monitor interval="10s" timeout="20s" \
        params ip="192.168.201.109"

Load the file to the cluster.

crm configure load update crm-vip.txt

In most installations, only the parameter ip needs to be set to the virtual IP address to be presented to the client systems. Use the command man ocf_heartbeat_IPAddr2 for details on additional parameters.

8.3.7 Constraints

The two constraints are organizing the correct placement of the virtual IP address for the client database access and the start order between the two resource agents SAPHana and SAPHanaTopology.

Example 34: Configure needed constraints
vi crm-cs.txt

Enter the following to :crm-cs.txt_:

colocation col_saphana_ip_<SID>_HDB<Inst> 2000: rsc_ip_<SID>_HDB<Inst>:Started \
    msl_SAPHanaCon_<SID>_HDB<Inst>:Master

order ord_SAPHana_<SID>_HDB<Inst> Optional: cln_SAPHanaTop_<SID>_HDB<Inst> \
    msl_SAPHanaCon_<SID>_HDB<Inst>
colocation col_saphana_ip_HA1_HDB00 2000: rsc_ip_HA1_HDB00:Started \
    msl_SAPHanaCon_HA1_HDB00:Master

order ord_SAPHana_HA1_HDB00 Optional: cln_SAPHanaTop_HA1_HDB00 \
    msl_SAPHanaCon_HA1_HDB00

Load the file to the cluster.

configure load update crm-cs.txt

8.4 Final Steps

8.4.1 Verify the Communication Between the Hook and the Cluster

Now check if the HA/DR provider could set the appropriate cluster attribute hana_<sid>_glob_srHook:

Example 35: Query the srHook cluster attribute
crm_attribute -G  -n hana_<sid>_glob_srHook

You should get an output similar to the following:

scope=crm_config  name=hana_<sid>_glob_srHook value=SFAIL

In this case the HA/DR provider sets the attribute to SFAIL to inform the cluster about a broken system replication.

8.4.2 Using special Virtual Host Names or FQHN During Installation of SAP HANA

If you have used special virtual host names or the fully qualified host name (FQHN) instead of the short node name, the resource agents need to map these names. To be able to match the short node name with the used SAP 'virtual host name', the saphostagent needs to report the list of installed instances correctly:

Example 36: In the setup at hand the virtual host name matches the node name
suse01:ha1adm> /usr/sap/hostctrl/exe/saphostctrl -function ListInstances
 Inst Info : HA1 - 00 - suse01 - 749, patch 418, changelist 1816226

8.4.3 End the Cluster Maintenance Mode

After all changes, as last step end the cluster maintenance mode.

crm configure property maintenance-mode=false

9 Testing the Cluster

Testing is one of the most important project tasks for implementing clusters. Proper testing is crucial. Make sure that all test cases derived from project or customer expectations are defined and passed completely. Without testing the project is likely to fail in production use.

The test prerequisite, if not described differently, is always that all cluster nodes are booted, are already normal members of the cluster and the SAP HANA RDBMS is running. The system replication is in synchronization represented by 'SOK'. The cluster is idle, no actions are pending, no migration constraints left over, no failcounts left over.

In the current version of this setup guide a plain list of test cases is provided. A more detailed description of the test cases is planned for future versions. These details will be provided either in an updated version of this guide or the test cases will be extracted to a seperate test plan document.

9.1 Generic Cluster Tests

The cluster tests described in this section cover the cluster reaction during operations. This includes starting and stopping the complete cluster or simulating SBD failues and much more.

  • Parallel start of all cluster nodes (systemctl start pacemaker should be done in a short time frame).

  • Stop of the complete cluster.

  • Isolate ONE of the two SAP HANA sites.

  • Power-off the majority maker.

  • Isolate the SBD.

  • Simulate a maintenance procedure with cluster continously running.

  • Simulate a maintenance procedure with cluster restart.

  • Kill the corosync process of one of the cluster nodes.

9.2 Tests on the Primary Site

The tests described in this section are checking the reaction on several failures of the primary site.

9.2.1 Tests Regarding Cluster Nodes of the Primary Site

The tests listed here check the SAP HANA and cluster reaction if one or more nodes of the primary site are failing or re-joining the cluster.

  • Power-off master name server of the primary. The test assumes that there is still an SAP HANA standby instance.

  • Power-off master name server of the primary after all standby instances are already in use.

  • Power-off any worker node but not the master name server of the primary. The test assumes that there is still an SAP HANA standby instance.

  • Power-off any worker node but not the master name server of the primary after all standby instances are already in use.

  • Power-off any standby node of the primary.

  • Re-join of a previously power-off cluster node.

9.2.2 Tests Regarding the Complete Primary Site

This test category is simulating a complete site failure.

  • Power-off all nodes of the primary site in parallel.

9.2.3 Tests Regarding the SAP HANA Instances of the Primary Site

The tests listed here are checks about the SAP HANA and cluster reactions triggered by application failures such as a terminated SAP HANA instance.

  • Kill the SAP HANA instance of the master name server of the primary. The test assumes that there is still an SAP HANA standby instance.

  • Kill the SAP HANA instance of the master name server of the primary after all standby instances are already in use.

  • Kill the SAP HANA instance of any worker node but not the master name server of the primary. The test assumes that there is still an SAP HANA standby instance.

  • Kill the SAP HANA instance of any worker node but not the master name server of the primary after all standby instances are already in use.

  • Kill the SAP HANA instance of any standby node.

  • Kill sapstartsrv of any SAP HANA instance of the primary.

9.3 Tests on the Secondary Site

The tests described in this section are checking the reaction on several failures of the secondary site.

9.3.1 Tests Regarding Cluster Nodes of the Secondary Site

The tests listed here check the SAP HANA and cluster reaction if one or more nodes of the secondary site are failing or re-joining the cluster.

  • Power-off master name server of the secondary. The test assumes that there is still an SAP HANA standby instance.

  • Power-off master name server of the secondary after all standby instances are already in use.

  • Power-off any worker node but not the master name server of the secondary. The test assumes that there is still an SAP HANA standby instance.

  • Power-off any worker node but not the master name server of the secondary after all standby instances are already in use.

  • Power-off any standby node of the secondary.

  • Re-join of a previously power-off cluster node.

9.3.2 Tests Regarding the Complete Secondary Site

This test category is simulating a complete site failure.

  • Power-off all nodes of the secondary site in parallel.

9.3.3 Tests Regarding the SAP HANA Instances of the Secondary Site

The tests listed here are checks about the SAP HANA and cluster reactions triggered by application failures such as a terminated SAP HANA instance.

  • Kill the SAP HANA instance of the master name server of the secondary. The test assumes that there is still an SAP HANA standby instance.

  • Kill the SAP HANA instance of the master name server of the secondary after all standby instances are already in use.

  • Kill the SAP HANA instance of any worker node but not the master name server of the secondary. The test assumes that there is still an SAP HANA standby instance.

  • Kill the SAP HANA instance of any worker node but not the master name server of the secondary after all standby instances are already in use.

  • Kill the SAP HANA instance of any standby node.

  • Kill sapstartrv of any SAP HANA instance of the secondary.

10 Administration

10.1 Dos and Don’ts

In your project, you should do the following:

  • Define (and test) STONITH before adding other resources to the cluster.

  • Do intensive testing.

  • Tune the timeouts of operations of SAPHanaController and SAPHanaTopology.

  • Start with PREFER_SITE_TAKEOVER=true, AUTOMATED_REGISTER=false and DUPLICATE_PRIMARY_TIMEOUT=”7200”.

  • Always make sure that the cluster configuration does not contain any left-over client-prefer location constraints or failcounts.

  • Before testing or beginning maintenance procedures, check if the cluster is in idle state.

In your project, avoid the following:

  • Rapidly changing/changing back cluster configuration, such as: Setting nodes to standby and online again or stopping/starting the master/slave resource.

  • Creating a cluster without proper time synchronization or unstable name resolutions for hosts, users, and groups.

  • Adding location rules for the clone, master/slave or IP resource. Only location rules mentioned in this setup guide are allowed.

  • As "migrating" or "moving" resources in crm-shell, HAWK or other tools would add client-prefer location rules, these activities are completely forbidden!.

10.2 Monitoring and Tools

You can use the High Availability Web Konsole (HAWK), SAP HANA Studio and different command line tools for cluster status requests.

10.2.1 HAWK – Cluster Status and more

You can use an Internet browser to check the cluster status. Use the following URL: https://<node>:7630

The login credentials are provided during the installation dialog of ha-cluster-init. Keep in mind to change the default password of the Linux user hacluster .

cluster status hawk 1
Figure 14: Cluster Status in Hawk

If you set up the cluster using ha-cluster-init and you have installed all packages as described above, your system will provide a very useful Web interface. You can use this graphical Web interface to get an overview of the complete cluster status, perform administrative tasks or even configure resources and cluster bootstrap parameters.

Read the product manuals for a complete documentation of this powerful user interface.

10.2.2 SAP HANA Studio

Database-specific administration and checks can be done with SAP HANA studio.

hana studio landscape
Figure 15: SAP HANA Studio – Landscape of a scale-out system
Note
Note

Be extremely careful with changing any parameter or the topology of the system replication. This might cause an interference with the cluster resource management.

A positive example is to register a former primary as new secondary and you have set AUTOMATED_REGISTER=false.

A negative example is to un-register a secondary, disable the system replication on the primary, and similar actions.

For all actions that change the system replication it is recommended to first check for the maintenance procedure.

10.2.3 Cluster Command Line Tools

crm_mon

A simple overview can be obtained by calling crm_mon. Using the option -r shows also stopped but already configured resources. Option -1 tells crm_mon to output the status once instead of periodically.

Stack: corosync
Current DC: suse05 (version 1.1.16-4.8-77ea74d) - partition with quorum
Last updated: Mon Jun 11 16:55:04 2018
Last change: Mon Jun 11 16:53:58 2018 by root via crm_attribute on suse02

7 nodes configured
16 resources configured

Online: [ suse-mm suse01 suse02 suse03 suse04 suse05 suse06 ]

Full list of resources:

stonith-sbd     (stonith:external/sbd): Started suse-mm
rsc_ip_HA1_HDB00        (ocf::heartbeat:IPaddr2):       Started suse02
 Master/Slave Set: msl_SAPHanaCon_HA1_HDB00 [rsc_SAPHanaCon_HA1_HDB00]
     Masters: [ suse02 ]
     Slaves: [ suse01 suse03 suse04 suse05 suse06 ]
     Stopped: [ suse-mm ]
 Clone Set: cln_SAPHanaTop_HA1_HDB00 [rsc_SAPHanaTop_HA1_HDB00]
     Started: [ suse01 suse02 suse03 suse04 suse05 suse06 ]
     Stopped: [ suse-mm ]

See the manual page crm_mon(8) for details.

SAPHanaSR-showAttr

To show some SAPHanaController and SAPHanaTopology resource agent internal values, you can call the program SAPHanaSR-showAttr. The internal values, storage location and their parameter names may change in the next versions. The command SAPHanaSR-showAttr will always fetch the values from the correct storage location.

Important
Important

Do not use cluster commands like crm_attribute to fetch the values directly from the cluster. Your methods will be broken, when you need to move an attribute to a different storage location or even out of the cluster. SAPHanaSR-showAttr is firstly a test program only and should not be used for automated system monitoring.

Example 37: Check SAPHanaSR-showAttr as user root
suse-mm:~ # SAPHanaSR-showAttr --sid=<SID>

The tool displays all interesting cluster attributes in three areas.

  • The global section includes the information about the cib time stamp and the attributes covering the status of the system replication

  • The site section includes the attributes per site and shows which site is the primary and the return code of the landscapeHostConfiguration.py script. In addition the active master name server is shown per site.

  • The hosts section includes the node status, the roles of the host inside the SAP HANA database, the calculated score to get the primary master name server and the site name the host belongs to.

Global cib-time                 prim sec  srHook sync_state
------------------------------------------------------------
global Tue Jun 12 15:02:58 2018 WDF1 ROT1 SOK    SOK


Site lpt        lss mns    srr
-------------------------------
WDF1 1528808568 4   suse02 P
ROT1 30         4   suse01 S


Hosts   clone_state node_state roles                        score site
-----------------------------------------------------------------------
suse-mm online
suse01  DEMOTED     online     master1:master:worker:master 100 ROT1
suse02  PROMOTED    online     master1:master:worker:master 150 WDF1
suse03  DEMOTED     online     master3:slave:worker:slave   80  ROT1
suse04  DEMOTED     online     master2:slave:worker:slave   110 WDF1
suse05  DEMOTED     online     master2:slave:worker:slave   80  ROT1
suse06  DEMOTED     online     master3:slave:worker:slave   110 WDF1

The majority maker suse-mm does not run an SAP HANA instance and therefore neither has a role attribute nor a score or site value.

10.2.4 SAP HANA LandscapeHostConfiguration

To check the status of an SAP HANA database and to figure out if the cluster should react, you can use the script landscapeHostConfiguration.py.

Example 38: Check the landscape status as user <sid>adm
HDBSettings.sh sh landscapeHostConfiguration.py

The landscape host configuration is shown with a line per SAP HANA host.

 | Host   | Host   | ... NameServer  | NameServer  | IndexServer | IndexServer |
 |        | Active | ... Config Role | Actual Role | Config Role | Actual Role |
 | ------ | ------ | ... ----------- | ----------- | ----------- | ----------- |
 | suse01 | yes    | ... master 1    | master      | worker      | master      |
 | suse03 | yes    | ... master 2    | slave       | worker      | slave       |
 | suse05 | yes    | ... master 3    | slave       | standby     | standby     |

 overall host status: ok

Following the SAP HA guideline, the SAP HANA resource agent interprets the return codes in the following way:

Table 3: Table Interpretation of Return Codes
Return CodeDescription

4

SAP HANA database is up and OK. The cluster does interpret this as correctly running database.

3

SAP HANA database is up and in status INFO. The cluster does interpret this as a correctly running database.

2

SAP HANA database is up and in status warning. The cluster does interpret this as a correctly running database.

1

SAP HANA database is down. If the database should be up and is not own by intention, this could trigger a takeover.

0

Internal Script Error – to be ignored.

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   under the terms of the GNU Free Documentation License, Version 1.2
   or any later version published by the Free Software Foundation;
   with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
   A copy of the license is included in the section entitled “GNU
   Free Documentation License”.

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the “ with…​Texts.” line with this:

with the Invariant Sections being LIST THEIR TITLES, with the
   Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.

If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.

If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.

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