NW 7.3: (A)SCS/SCS/ERS - use the same IP

[Former Member]

Hi,

evaluation tests with SAP NW 7.3 show that the instances of (A)SCS and ERS just using the same IP (in previous release ASCS and SCS have their own IP; depending on the releases ERS request an IP or not for installation procedure).

In a single host environment the new behavour doesn't matter. If you operate in a virtualized environment (where each instance type can run at any host with its own IP at th same time) it will not work furthermore. You can't use the same IP on different hosts at the same time.

So I have two questions

1.) Is it possible to reorganize the installation according to the previous conditions used in older SAP NW releases

2.) If answer of question 1) is 'yes', what does it mean if I use ACC to control/administer my SAP landscape

3.) If answer of question 1) is 'yes', what does it mean for the support of such installations by SAP

Kind regards

Karlheinz

[Former Member]

Hi Karlheinz Heger

With ASCS (ms + enq) SAP also introduced an ERS (enqueue replication server) to provide high availability for the enqueue server.

ERS is a standalone component and it runs on another host and connects with the enqueue server. Once connected, the enqueue server sends lock table replication data to the replication server. The replication server maintains a shadow lock table with the replication data. The shadow lock table exists in the shared memory and is used to rebuild lock table for the failed enqueue server when it is restarted on the same host where the replication server is running. Thus, the host where the standalone enqueue server is running and the host where the replication server is running must be clustered so that failed enqueue server can be restarted on the host where the shadow lock table is maintained. Once the enqueue server rebuilds the lock table from the shadow lock table, the replication server is shutdown.

So in nutshell you need to install ERS and ASCS on seprate host if you want real hig availability without failed transaction.

If you have ERS and ASCS on same host it would not be HA.

Hope this helps

[sunny_pahuja2]

Hi,

Installation for ASCS/SCS/ERS depends whether system is highly available or not. If system is based upon high availability then you have to plane for ASCS/ERS. If it is a simple system without HA then you need not to have ASCS and ERS separately.

If you want to change from HA config to without HA then it is possible and you have to do this with system copy method.

Thanks

Sunny