Share with friends and colleagues on social media

This blog post aims to summarize the starting and stopping options available for SUSE Linux Enterprise Server (SLES) High Availability (HA) cluster stack operations. I will offer brief answers to a few questions that have been commonly asked by our customers and partners.

Before We Start:

First, some background information, SUSE Linux Enterprise (SLE) High Availability Extension (HAE) team sets a specific systemd unit parameter StopWhenUnneeded=yes inside the corosync.service systemd unit configurations file /usr/lib/systemd/system/corosync.service.

What this means is only systemctl stop pacemaker command execution will stop the corosync service when corosync service thinks it is no longer needed. A common misconception is that SLES HA cluster operators think they could restart the whole cluster stack on one node using systemctl restart pacemaker command, which is not correct.

Tip

For more information about StopWhenUnneeded=yes parameter explanation, please refer to systemd.unit man page.

Upcoming Change:

The SLE HAE team plans to drop the parameter StopWhenUnneeded=yes from SLE 15 SP2 and the newer releases. SLES HA cluster operators are encouraged to use the Cluster Resource Manager Shell (CRMSH) commands to avoid any confusion.

The following table lists the main SLES HA cluster stack starting and stopping operations using CRMSH commands:

SLES HA Cluster Operation CRMSH Command
Starting the cluster stack on one node crm cluster start
Stopping the cluster stack on one node crm cluster stop
Restarting the cluster stack on one node crm cluster restart
Getting the cluster stack status on one node crm cluster status

Note

All of the above-mentioned commands in the above table should be executed by an operation user who has the required privileges or by the root user.

Tip

For more info about the above-mentioned crm commands, please refer to crm cluster help help messages.

Cluster Stack Control using systemctlcommand:

Although we at SUSE recommend using CRMSH commands for the SLES HA cluster stack operations, you are still able to use the systemd commands to start, restart and stop SLES HA cluster stack as follows:

SLES HA Cluster Operation systemd Commands
Starting the cluster stack on one node systemctl start pacemaker
Stopping the cluster stack on one node systemctl stop corosync
Restarting the cluster stack on one node systemctl restart corosync

 

Note

  • Starting pacemaker service will first start the corosync one.
  • Stopping corosync service will first stop the pacemaker one.

Summary:

We at SUSE recommend using CRMSH commands that provide a clear option to control your cluster stack.

This is Abdelrahman Mohamed (Ab) from SUSE Software Alliances team.
Share with friends and colleagues on social media

Category: Alliance Partners, Cloud Computing, SUSE Linux Enterprise High Availability Extension, Technical Solutions
This entry was posted Thursday, 31 October, 2019 at 8:40 am
You can follow any responses to this entry via RSS.

Leave a Reply

Your email address will not be published. Required fields are marked *

No comments yet