Tuesday, May 27, 2014

GroupCalcPollingIntervalMilliseconds in SCSM 2012 Causes Queue Membership Issues

This TechNet article recommends changing the GroupCalcPollingIntervalMilliseconds registry entry to 1000000 to improve performance of System Center Service Manager. It is supposed to reduce the frequency with which Service Manager calculated group membership used within user roles to 10 minute intervals, which improves performance in large environments. There are three issues with this recommendation:

  1. 1000000 milliseconds is not 10 minutes, it's ~17 minutes. Minutes are not in base ten. If you want to set this key after reading the following bullet points, make sure you do your math correctly.
  2. This registry key impacts the application of SLOs to work items, as the GroupCalcPolling process is responsible for this.
  3. This registry key also impacts the process that relates a work item to a queue. If you're scoping what work items users can see by queue criteria, work items will only be added to queues within the specified interval.

This means that a user will not see work items scoped to them until the GroupCalcPolling process runs at the specified interval. By the same token, SLOs will not be applied until this interval elapses as well.

Obviously numbers 2 and 3 are an issue in all but the smallest environments, so use extreme caution when setting this key. It will improve performance, but it will impact other, potentially critical, areas within Service Manager that the SCSM team has apparently not documented.