HA Scenario in SAP Webdispatcher

[ulrich_sander]

Hello all,

I have read the documentation of the different HA scenarios for SAPWebDispatcher in:

https://help.sap.com/doc/saphelp_nw73ehp1/7.31.19/en-US/48/9a9a6b48c673e8e10000000a42189b/frameset.h...

There is one scenario which comes very near to what I want to design:

But I have had a different idea about the FailOver-Scenario because I started my design prior to knowing the content of the site above.

Currently we don't want to use a hardware load balancer, but I thought about a scenario similar to HANA takeover/failover.

This means that there is one IP-address whitch is binded to one of the two different SAP WebDispatcher instances and could be switched from one SAP-WebDispatcher instance to the other standby instance with a different SID but the same config. So this means we have instead of hardware based load balancer a simple workflow that switches the relevant IP address between the to different instances if we want to (because of a maintenance) or we have to (because of a failure in the current active SAP WebDispatcher). Again: the configuration of the two SAP WebDispatches is identically regarding ports,redirections and backend systems.

I made the following test: I was logging into the webgui through SAPWebDispatcher 1. Then I switched to SAPWebDispatcher 2 (simply by unbinding the virtual IP address on WDP1 and set it to WDP2. After that I was able to continue navigating in max webgui as if nothing has happened.

I this scenario valid?

Thanks

Ulrich Sander

[ulrich_sander]

Unfortunately the screenshots from the help.sap.com are not visible in my text. Please open the link in my text and see the two figures "High Availability Cluster" and "Parallel Web Dispatcher".

[cris_hansen]

Hi Ulrich,

I would say: check the web dispatcher trace (dev_webdisp) and see whether the requests are being sent to the same backend system. Check also in the backend system (in the ICM trace, dev_icm) whether the requests from the WEBGUI session are still coming ok. If the traces are showing all ok for you, then your scenario is valid. (In log we trust).

Nevertheless, maybe you can add the tag NW Client/Server Technology (CST), so folks from CST (web dispatcher belongs to them) can give their hints as well.

Regards,

Cris

PS: Have you already visited the SAP Web Dispatcher wiki page? Maybe there are additional info there.