User traffic going to a specific webengine

Products

• CA Service Management - Service Desk Manager
• CA Service Desk Manager

Issue/Introduction

End users are running with an external F5 load balancer.  The expected webengine end users are supposed to use is the one that ends in "pdmweb.exe" but end users are being sent to a webengine on the same server that uses "pdmweb1.exe".  Need to know what is causing this behaviour.

Environment

Release : 17.3

CA Service Desk Manager

Cause

The pdm_status on the given server shows that there is a defined set of webengines and also a Web Director.

Unless carefully architected, it is not advised to have both the SDM Web Director and a third party load balancer such as F5, both of which can distribute web traffic, and have the potential to interfere with each other.

Resolution

Short term solution is to modify the web.cfg to disable web director based load balancing.  The setting of interest is.  

! UseDirector no

Adjusting this setting in web.cfg to be uncommented and set to "no" successfully resolves the F5 load balancing problems that favoured pdmweb.exe over pdmweb1.exe the given app server, and the same will likely be needed on any other app servers with a similar configuration of multiple webengines and active web directors.

Long term solution is to re-examine the existing architecture to determine where is all webengine traffic going to per app server (run pdm_webstat periodically).  If all users are going to pdmweb.exe per app server, consider removing the existing pdmweb1.exe webengine AND the established web director load balancer, using just F5 as the exclusive load balancing solution.

Additional Information

Any examination of system architecture is outside the scope of Support.