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excessive vmotions on vCenter start

Overview

When a Virtual Center with a large number of hosts starts (either controlled or after a failure) a large number of vMotions have been initiated by DRS. Although this doesn’t directly cause an issue, it does impact the performance of the environment. A few days ago we noticed VMware posted kb2107950 acknowledging the issue.

Solution

To address the issue its necessary to update the vpxd.cfg file as directed in the article.

<vpxd>
 <quickStats>
  <HostStatsCheck>true</HostStatsCheck>
 </quickStats>
 <drmMinQuickStatsPerc>90</drmMinQuickStatsPerc>
</vpxd>

After updating the VC configuration you must restart the service, and you should no longer get the rush of vMotions we’ve witnessed previously.

Note: The default value is 50%, this means that by default once half the hosts controlled by a VC have posted quickstats, it begins calculating vMotions, this setting increases this to 90% of hosts, so the VC will have more information upon which it can base its decisions.

References

kb2107950

FIN