ERS for ASCS SCS HA installation

[Former Member]

Hello Experts,

We are planning to install SAP XI in cluster environment (linux 7.1, Oracle 12c and VCS). We will install only CI, ASCS/SCS instance and no DI.

want to confirm my understanding if we need ERS in to be installed in this case ?

we will install Node 1

/usr/sap/SXP/ERSxx - local

below in cluster filesystem
/usr/sap/SID (DVEBMGSxx)

/usr/sap/SXP/ASCSxx

/usr/sap/SXP/SCSxx

/sapmnt/SID

/usr/sap/trans

Node2

/usr/sap/SXP/ERSxx - local

In this architecture, do we need ERS to be setup locally or its not needed. is it needed to ensure replication when DVEBMGSxx, ASCS and SCS services failover from N1 to N2. Can you get some light on this understanding ?

Regards, Swapnil

[former_member252185]

Experts, can you tell me if I have to use virtual host name or host name to install ERS in unix vcs cluster setup?

the latest unix document says to use virtual host name when installing ERS in first host. for second host as well, do I have to use virtual host name or host name?

[isaias_freitas]

Hello,

The ERS is the "Enqueue Replication".

It connects to the enqueue (running at the ASCS/SCS) and keeps a copy of the lock table.

Thus, if the node where the ASCS/SCS is running fails, the cluster move the ASCS/SCS to the other node.

Once the ASCS/SCS is started there, it will take over the copy of the lock table that the ERS was keeping.

But, since your CI would also be at the clustered disk, once the node fails the CI will go down as well and all your end users will lose the connection to SAP.

This is not a "standard SAP installation" (to put the CI in cluster as well).

The ERS could still help (e.g., pending update requests with associated locks might still be able to be processed), but I think your setup tends to make the ERS unnecessary.

Regards,

Isaías

[AtulKumarJain]

Hi Swapnil,

If you got your answer please close the thread.

BR

Atul

[Former Member]

Full RedHat documentation for HA Clustering can be found here.  I double checked, and though it shows RHEL 6, it seems to remain valid for 7 (they have not updated it for RHEL 7).  Hope this helps!

https://access.redhat.com/sites/default/files/attachments/rh-pacemaker-sap-whitepaper.pdf

[AtulKumarJain]

Hi Swapnil

I will say yes you have to install;Please go through below link to understand this

Enqueue Replication Server Part 1 - What is ERS - Netweaver Technology - SCN Wiki

Please follow the below whitepaper for setup.

http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/b005dffd-62c5-3010-3cbb-fda4b493d...

BR

Atul