Slow Performance with Dell PERC Controller

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• 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.

Environment

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

Resolution

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:

• Seagate SAS drive numbers ST3450856SS, ST3300656SS and ST3146356SS firmware version HS0A

There is a newer firmware release available that also improves 4k random reads:

• Seagate SAS ST3450856SS, ST3300656SS and ST3146356SS firmware version HS0F

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.