Slow Performance with Dell PERC Controller
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Slow Performance with Dell PERC Controller


Article ID: 326325


Updated On:


VMware vSphere ESXi


  • Slow performance experienced in SQL and Exchange virtual machines running on local storage using the Dell PERC controller with Seagate drives.
  • Sequential reads and writes cause poor performance.
  • Longer than normal boot up/shutdown period for ESXi/ESX hosts.
  • You may experience slow migration to and from the local disk.


VMware ESXi 3.5.x Installable
VMware ESX 4.0.x
VMware ESXi 3.5.x Embedded
VMware ESX Server 3.0.x
VMware ESXi 4.0.x Installable
VMware ESX Server 3.5.x
VMware ESXi 4.0.x Embedded


There is a known issue with the Seagate drives managed by Dell PERC controllers with regard to sequential read and write performance. As a result, the DAVG values in the disk view of esxtop are abnormally high.

Virtual machines doing sequential reads and writes, such as mail or SQL servers, are affected by this issue.

Dell has released a firmware update for the drives to address the issue: There is a newer firmware release available that also improves 4k random reads: Potentially affected systems are:
  • PowerEdge 1950
  • PowerEdge 2900
  • PowerEdge 2950
  • PowerEdge 2970
  • PowerEdge 6850
  • PowerEdge 6950
  • PowerEdge 1900
  • PowerEdge 840
  • PowerEdge 860
  • PowerEdge R200
  • PowerEdge R300
  • PowerEdge R900
  • PowerEdge R905
  • PowerEdge T100
  • PowerEdge T105
  • PowerEdge T300
  • PowerEdge T605
  • PowerVault MD1000
For more information on this firmware release, contact Dell support.