Chapter 4. Configuring the ASCS and ERS instances

Procedure

1. Register the ASCS instance. Run the following SAP command as the root user to create the systemd integration:

   [root]# export LD_LIBRARY_PATH=/usr/sap/<SID>/ASCS<instance>/exe && \
   /usr/sap/<SID>/ASCS<instance>/exe/sapstartsrv \
   pf=/usr/sap/<SID>/SYS/profile/<SID>_ASCS<instance>_<ascs_virtual_hostname> \
   -reg

   The command executes the sapstartsrv service for the selected instance profile and registers the instance service on the current system. It creates the systemd unit for the instance service, if it does not exist, and updates the local /usr/sap/sapservices file.

   • Replace <SID> with your ASCS instance SID, for example, S4H.
   • Replace <instance> with your ASCS instance number, for example, 20.
   • Replace <ascs_virtual_hostname> with the virtual hostname for your ASCS instance, for example, s4hascs.

2. Register the ERS instance by repeating step 1 for the ERS profile:

   [root]# export LD_LIBRARY_PATH=/usr/sap/<SID>/ERS<instance>/exe && \
   /usr/sap/<SID>/ERS<instance>/exe/sapstartsrv \
   pf=/usr/sap/<SID>/SYS/profile/<SID>_ERS<instance>_<ers_virtual_hostname> \
   -reg

   • Replace <SID> with your ERS instance SID, for example, S4H.
   • Replace <instance> with your ERS instance number, for example, 29.
   • Replace <ers_virtual_hostname> with the virtual hostname for your ERS instance, for example, s4hers.

3. Optional: Register any PAS or AAS instance by repeating step 1 for the respective application server profile. Skip this step if you do not configure PAS or AAS instances in this cluster:

   [root]# export LD_LIBRARY_PATH=/usr/sap/<SID>/D<instance>/exe && \
   /usr/sap/<SID>/D<instance>/exe/sapstartsrv \
   pf=/usr/sap/<SID>/SYS/profile/<SID>_D<instance>_<as_virtual_hostname> \
   -reg

   • Replace <SID> with your PAS or AAS instance SID, for example, S4H.
   • Replace <instance> with your PAS or AAS instance number, for example, 21.
   • Replace <as_virtual_hostname> with the virtual hostname for your PAS or AAS instance, for example, s4hpas.

4. Disable the ASCS, ERS and any other application instance service that the cluster manages after the setup:

   [root]# systemctl disable SAP<SID>_<instance>.service
   Removed "/etc/systemd/system/multi-user.target.wants/SAP<SID>_<instance>.service".

   Run this using the ASCS instance number and repeat the command using the ERS instance number.

   Optional: Repeat the same for the PAS or AAS instance services.

5. Create the systemd drop-in directory for the ASCS, ERS and any other application instance service that the cluster manages after the setup:

   [root]# mkdir /etc/systemd/system/SAP<SID>_<instance>.service.d

   Run this using the ASCS instance number and repeat the command using the ERS instance number.

   Optional: Repeat using the PAS or AAS instance number.

6. Create the drop-in files for the instances in the new directory:

   [root]# cat << EOF > /etc/systemd/system/SAP<SID>_<instance>.service.d/HA.conf
   [Service]
   Restart=no
   EOF

   Run this using the ASCS instance number and repeat the command using the ERS instance number.

   Optional: Repeat using the PAS or AAS instance number.

7. Reload the systemd units to activate the drop-in configuration:

   [root]# systemctl daemon-reload

8. Repeat all steps on each cluster node for every instance.

Verification

1. Check that all instances have instance systemd units and that they are disabled:

   [root]# systemctl list-unit-files SAPS4H*
   UNIT FILE         STATE    PRESET
   SAPS4H_20.service disabled disabled
   SAPS4H_29.service disabled disabled

   Optional: PAS or AAS instance service files are listed as well in all of the verification steps when you have configured the application server instances.

2. Check that the sapservices file contains entries for every instance:

   [root]# cat /usr/sap/sapservices
   systemctl --no-ask-password start SAPS4H_20 # sapstartsrv pf=/sapmnt/S4H/profile/S4H_ASCS20_s4hascs
   systemctl --no-ask-password start SAPS4H_29 # sapstartsrv pf=/sapmnt/S4H/profile/S4H_ERS29_s4hers

3. Check that all systemd configuration overrides are present:

   [root]# systemd-delta | grep SAP
   ...
   [EXTENDED]   /etc/systemd/system/SAPS4H_20.service  /etc/systemd/system/SAPS4H_20.service.d/HA.conf
   [EXTENDED]   /etc/systemd/system/SAPS4H_29.service  /etc/systemd/system/SAPS4H_29.service.d/HA.conf

4. Repeat the steps on every cluster node. The results must be the same on all nodes.

Procedure

1. Stop the instance on the node where it currently runs, for example, stop ASCS on node1:

   [root]# systemctl stop SAP<SID>_<instance>.service

   Stopping the SAP instance systemd service stops both the instance service and the instance itself.

2. Start the instance service sapstartsrv on the node where it was not running before, for example, start the ASCS service on node2:

   [root]# systemctl start SAP<SID>_<instance>.service

3. Start the instance using sapcontrol as the <sid>adm user. Replace <instance> with the instance number, for example, 20 for the ASCS instance:

   <sid>adm $ sapcontrol -nr <instance> -function Start

4. Verify the instance’s health after it starts on the other node. Run this check as the <sid>adm user. Replace <instance> with the instance number, for example, 20 for the ASCS instance. The status of all services must be GREEN:

   <sid>adm $ sapcontrol -nr <instance> -function GetProcessList

5. Optional: Repeat the previous steps to move the instance back to its original node, for example, move ASCS back to node1.
6. Repeat all steps for the ERS instance.
7. Optional: If you configure PAS or AAS instances, then repeat the steps for these application server instances as well.