Virtual machine performance degrades while a vMotion is being performed

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• Cannot perform vMotion to migrate a virtual machine from ESXi 5.x host to another
• Performing vMotion to migrate a virtual machine from ESXi 5.x 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

Environment

VMware vSphere ESXi 5.5
VMware vSphere ESXi 5.0
VMware vSphere ESXi 5.1

Cause

This issue occurs because vSphere 5.0 introduces a new feature called Stun During Page Send (SDPS) to ensure more active, large memory virtual machines that are successfully vMotioned from one host to another.

SDPS intentionally slows down the vCPUs to keep the virtual machine's memory from being faster.This guarantees that the vMotion operation ultimately succeeds impacting the performance while vMotion is in progress.

Resolution

To work around this issue, the Stun During Page Send (SDPS) feature can be disabled on a per-host basis.

To disable Stun During Page Send (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.

Additional Information

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Impact/Risks: