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Virtual machine performance degrades while a vMotion is being performed (2007595)

Symptoms

  • When using vMotion to migrate a virtual machine from ESXi 5.0 host to another, the performance of the virtual machine degrades
  • The virtual machine is very active and consumes a large amount of memory, database, or mail server.

Cause

vSphere 5.0 introduces a new feature called Stun During Page Send (SDPS) to ensure that more active, large memory virtual machines are successfully vMotioned from one host to another. SDPS intentionally slows down the vCPUs just enough to keep the virtual machine's memory from being dirtied faster than it can be copied from one host to another if it is detected that vMotion will not succeed otherwise. While this guarantees that the vMotion operation will ultimately succeed, it may impact the performance while vMotion is in progress.

Resolution

To workaround this issue, the Stun During Page Send feature can be disabled on a per-host basis.
 
To disable SDPS for all virtual machines on a particular host:
  1. In the vSphere client, select the host and then click the Configuration tab.
  2. Under Software, click Advanced Settings.
  3. Click Migrate in the left side and the scroll down to Migrate.SdpsEnabled on the right side.
  4. Change the value of Migrate.SdpsEnabled to 0.
  5. Click OK.

Note: This change must be applied to all hosts in the cluster.

Impact/Risks

vMotion of highly active virtual machines may fail when SDPS is disabled. There is also a higher probability that metro vMotion (vMotion over a link with up to 10ms of latency) might fail as the virtual machine's memory is dirtied faster than it can be copied over the slower link.

Tags

poor-performance

Update History

02/04/2013 - Minor formatting corrections.

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