A little while ago, on February 23rd to be exact, SUSE Linux Enterprise Server for SAP Applications based on SLES 12 SP1 was announced. Unfortunately due to a packaging snafu that only effected the release on AWS we were not able to release updated Bring Your Own Subscription (BYOS) images in AWS EC2 at that time. This has now been addressed and you can find the latest images by searching for suse-sles-sap-12-sp1-byos in the general catalog in AWS. All SUSE images contain a date stamp in the name, such as v20160308, to make it easy to always identify the latest image. In addition the pint command line tool will provide the information as well.
pint amazon images –active –filter ‘name~sap,name~sp1’
With this release the HA stack that is part of SUSE Linux Enterprise Server 12 SP1 for SAP Applications is fully supported. The image contains the ec2 STONITH agent to handle fencing and the aws-vpc-move-ip package that properly handles routing and the IP address on failover in a VPC setting.
Detailed information about an HA setup in AWS is described in High Availability Solutions for SAP on AWS.
The STONITH fencing agent is used when the HA cluster detects issues with the network and a so called “split brain” condition is detected. At this point the ec2 fencing agent shuts of the secondary node to avoid any issues the “split brain” condition would cause. The ec2 STONITH agent uses the aws command line tool (also included in the image) and thus when setting up the HA cluster the aws tool must be configured to work properly. This includes creating a configuration file for the aws command line tool. Please refer to the aws-cli documentation for details. The aws-cli package is part of the SUSE Linux Enterprise Public Cloud Module and thus when you set up the repositories in your BYOS instances you want to add the Public Cloud Module repository using YaST or SUSEConnect.
SUSEConnect –url YOUR_UPDATE_SERVER_URL \
The second part of an HA setup is the redirection of traffic when one node falls over. This is handeled by the code in the aws-vpc-move-ip agent. This code will fix up the routing table in a VPC by setting up a /32 route to point to the appropriate instance. This also depends on the aws command line tools.
Last but not least don’t forget that SAP HANA is set up as a Quick Start in AWS EC2.
And as a little teaser let me share that there will be more news about SUSE Linux Enterprise for SAP applications in the not too distant future, thus stay tuned to the various SUSE channels for more information.