Enqueue Replication Server HA

[Former Member]

Dear friends, we are planning an HA instalation, but we have a doubt about the Enqueue Replication Server. As per my understanding, we can install en enqueue replication server (ERS) in other host (B), but in case of fail over, the sap instance needs to be started in the same host of the ERS (B) to be able to access to the lock table of the ERS.

Do you know if posible to instal the ERS in other host, and the sap instance in another? The scenario looks like:

Before Fail Over:

Host A: ASCS + CI.

Host B: Stand by Server for the failover.

Host C: ERS.

After Fail over:

Host A: Stand by Server for the failover.

Host B: ASCS + CI.

Host C: ERS.

Will be possible for the host B read the replicated lock table in the host C after the fail over?

The documentation says that the replicated lock table is stored in a shared memory area, then, when the instance is started in the other host (failover) is cappable to read this information form the shared memory area. But what happens if the ERS is in a separated host?

Thanks and best regards.

Hector.

[tomislav_bobanovic]

Hello Hector,

I install HA environment with two nodes with ASCS, ERS, D01 and D02.

All 4 instances can switch between those two nodes and in all scenarios system working properly.

You just need to install all instances on VIP which also must be able to switch between nodes together with instances.

Br

Tomislav

[Former Member]

Hi Tomislav,

I have a question, As I know ASCS and ERS should be running on same host.

Then, ASCS and ERS, both of all have to have a virtual IP address?

Regards,

Jinkoo

[tomislav_bobanovic]

Hi Jinkoo,

running ASCS and ERs on the same host is not a "must". They can run on different hosts also.

If you separate all the instances because of HA, I will recommend you to use separate VIP for each instance.

Br

Tomislav

[Former Member]

Hi Tomislav,

Thank you for your reply.

Then you said, "to use separate VIP for each instance.". what is each instance? I mean the instance is ERs and ASCS? or the each instance indicate to ASCS instances?

I think you indicated the instances are ERs and ASCS. then Why does ERs need a virtual IP address? because as I know ERs connect to ASCS. so I think ERs doesn't need a virtual IP. but if there has ERs client, the ERs must have a virtual IP for connection. is it right?

Regards,

Jinkoo

[Isaias_SAP]

Hello,

The ERS must be running on a different host.

Otherwise, having an ERS is not helpful.

Read High Availability with the Standalone Enqueue Server - Standalone Enqueue Server - SAP Library .

Cheers!

Isaías