1 Reply Latest reply on Aug 30, 2018 12:54 PM by dbuenoparedes

    DRS Migration threshold 2 higher sensitivity after update

    dbuenoparedes Novice

      Just throwing the question out to see if anyone else has experience anything similar. I did some searches but couldn't find anything on the release notes nor on this community nor on other forums about this issue.


      We have set on some of our production clusters the DRS Migration threshold to 2, that way we minimize the number of VM moves (vMotion) on those cluster while keeping all the hosts busy with workload. The rate of the moves was (more or less):


      • Before the update:
        • Week of Aug 2nd to 8th:
          • Thursday: 2 vMotions
          • Friday: 2 vMotions
          • Saturday: 0 vMotions
          • Sunday: 5 vMotions
          • Monday: 11 vMotions
          • Tuesday: 5 vMotions
          • Wednesday: 2 vMotions
        • Total: 27


      • After the update:
        • from Aug 23rd to Aug 30th:
          • Thursday: 12 vMotions
          • Friday: 9 vMotions
          • Saturday: 0 vMotions
          • Sunday: 7 vMotions
          • Monday: 20 vMotions
          • Tuesday: 14 vMotions
          • Wednesday: 2 vMotions
        • Total: 64


      The only change in the environment has been updating vCenter server for Windows v6.0 U2 to v6.0 U3f, no change in workload, no other configuration changes, ESXi versions of the hosts haven't changed either. This is just an example of one location but we have more locations that have experienced the same behavior: an increase that doubles (or even more) the number of vMotions triggered by DRS.


      We'll open a ticket with VMware about this but I was wondering if anyone else has experienced this change in DRS behavior.

        • 1. Re: DRS Migration threshold 2 higher sensitivity after update
          dbuenoparedes Novice

          After some more digging and playing around with VMware's tool DRS Dump Insight (which, btw, doesn't seem to work with Update 3f drmdumps, they show them all as corrupted) doing a search of a flag feature that DRS Dump Insight shows when you do a what-if simulation, we found the following KB: VMware Knowledge Base - DRS migrates VMs when the cluster appears/shows balanced after upgrading to vCenter Server 6.0 U3 or 6.5 that seems to be exactly what is causing the big amount of vMotion moves.


          We'll do some testing to confirm the resolution of the KB works.


          Edit: Seems that the instructions on the KB did the trick. (/ironymodeon) Thanks VMware for making this the default behavior instead of something optional via an advanced setting (/ironymodeoff)