Cluster Web Dispatcher together with CI in MSCS?

[Former Member]

I need to provide HA for Web Dispatcher by clustering in MSCS. My plan is to share the MSCS of the CI it is connecting to. The CI (ASCS and SCS) is already installed in cluster with all proper shared resources (disk, global share, services, ip, netname, etc.) My question is whether I should or need to create a separate cluster group for the WD or if it would be easier/better to install in same shared disk as CI? I have been referring to SAP Note 834184 regarding the manual install of the WD in MSCS and have run into an issue because of the global share of the CI. Currently the WD is installed on its own shared disk (with directory structure), and its own netname and IP. When starting it is trying to access the SAPMNT share of it's host, which is successful (as the hostnames and ip are really just virtual resources of the cluster), but the directory path it tries to access on the share is not correct because the share is really for the shared disk of the CI and not that of the WD.

Does anyone have a recommended method of clustering the WD in an existing SAP MSCS cluster? It seems that the Note referenced above was not written with this in mind. However, due to the very low resource needs of the WD, I think it would be fairly common to cluster it with an existing installation or the msg server it is serving. My next thought is to install the WD on the same shared disk and cluster group as the CI and allow it to fail over with the CI so it will access the proper sapmnt file share, but I'm not sure if this is the recommended or best practice for this type of scenario.

Thank you for any input on this and I would be happy to provide any futher details of my configuration.

thanks,

John

[Former Member]

John,

First, lets clarify the confusion: CI is not where your ASCS and SCS are installed.

"The system consists of two instances: a Java central instance with SDM, and the Central Services instance"

http://help.sap.com/saphelp_nw04s/helpdata/en/43/1af03eae11e16be10000000a114084/frameset.htm

(A)SCS - "(ABAP) SAP Central Services", consists of Message Server and Enqueue Server, resides in a cluster group of MSCS

CI - "Central Instance" - Dispatcher, Server Processes and SDM. Not part of cluster group, resides on C: drive (your case).

Now to the point:

It is absolutely OK to install your Web Dispatcher on the cluster group of your (A)SCS.

You can use shared drive as a location for the Web Dispatcher and PFL file.

In this case you do not need to do step "6. Register the SAP Events DLL in registry" from note 834184.

During the failover, Web Dispatcher comes up properly on the target node.

Let me know if you need step by step instructions.

I can send you screenshots for the install.

Regards,

Slava

[Former Member]

I'm sorry about the confusion regarding the CI. I mis-wrote when referring to the "CI" in my post, as I understand that it does not contain the central services (ASCS and SCS) that are the SPOFs in a dual stack system.

Thank you for the feedback regarding the placement of the web dispatcher. I will move the WD installation to the existing clustered disk of the Central Services and see how the rest of the configuration goes. I did think to disregard the SAP Events DLL step as this already exists on both MSCS nodes.

thanks again,

John