Checking SAP application ASCS/ERS status

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ASCS / ERS status

As explained at https://blogs.sap.com/2021/10/28/sap-ascs-high-availability-using-ers-explained/ we use ASCS / ERS replication to ensure high availability of application. For checking whether ASCS / SRS are running on which nodes we can use either cluster command such as:

#RHEL
pcs cluster status   #OR pcs status

#Suse
crm status

This would show ASCS resource group running on primary while ERS resource group running on secondary

Other option is to look at running processes. If cluster is functioning properly then on primary we can see ascs via:

ps -eaf | grep -i ascs

while we can see ers on secondary via

ps -eaf | grep -i ers

On primary we would also see following mount points:

• /sapmnt
• /usr/sap/trans
• /usr/sap/<ID>/ASCS01

While on secondary we would see following mount points:

• /sapmnt/
• /usr/sap/trans
• /usr/sap/<ID>/ERS02

Both ASCS and ERS have their own floating IP. During failure all resources come to a single machine.

During failover from primary mount point

• /usr/sap/<ID>/ASCS01

would additionally get mounted on secondary node and also virtual IP would migrate from primary to secondary node. After this if primary node comes back then ERS would start on primary node and ASCS would continue to run on secondary node itself.

SAP Application Status

ASCS and ERS are only for lock table replication. The application can still be down when they are running. To check whether application is running or not use:

ps -eaf | grep -i d0

Note that in case of application clustering is only used to manage the replication for lock tables via ASCS/ERS. Start/stop of application should be done manually for SAP team.

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