excessive vmotions on vCenter start04 Mar 2015
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.
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.