HA in Windows + SQL Server - in NW 7.0

[Former Member]

Hi all,

I have to install an ABAP-only SAP ERP 2005 system using High Availability in Windows 2003 + SQL Server 2005 for my customer.

There's no way else except using MSCS so SAP can support me in case of problem?

After reading SAP installation guide (ERP 2005 SR2 ABAP on Windows SQL Server), I find 2 one-cluster options:

- Option 1:

+ Machine 1: 1st MSCS node: ASCS, DB instance, and CI.

+ Machine 2: Additional MSCS node: ASCS, DB instance, and DI.

- Option 2:

+ Machine 1: 1st MSCS node: ASCS, DB instance.

+ Machine 2: Additional MSCS node: ASCS, DB instance

+ Machine 3: 1 CI node.

+ Machine 4: 1 or more Dialog instance.

Unfortunately, the installation guide says that CI is a non-SPOF and my customer wants a MSCS with full clustered so the CI have to be clustered also. Customer also wants to use 3 machines only, they don't want to use 4 machines to save cost.

At first thougth, I think the infrastructure is:

- Machine 1: 1st MSCS node: ASCS, DB instance

- Machine 2: 1 CI node

- Machine 3: additional MSCS node: ASCS, DB instance, and CI.

Machine 1 & machine 2 make the primary application server instance, machine 3 is for case of failover.

I don't know my infrastructure is right or not with 2 CIs. What I want is to make a full clustered solution with 3 machines.

Someone with experience please help me.

Thanks a lots,

Toan Do

[klaus-georg_adams]

Hi Toan Do,

you can't install more than one CI in the system. In a setup, where an ASCS instance is installed, the CI is indeed not a single point of failure and does not have to be clustered. I you want redundancy, install additional dialog instances.

Even if the central instance is not clustered, the system will continue working in both options suggested by SAP if the CI falls down.

If you absolutely want to use 3 machines, go for option 1 and install an additional dialog instance on the third machine.

HTH

Klaus-Georg Adams