vCenter Server 4.0 vMotion operation fails with the error: Insufficient disk space on datastore

Products

• VMware

Issue/Introduction

Symptoms:

Migrating virtual machines between two ESX hosts that store the virtual machine swap files in different locations, may exhibit these symptoms:

• A vMotion operation fails
• When attempting to migrate, you see the error:
  
  Insufficient disk space on datastore '<Datastore Name>'.

Cause

If you are migrating virtual machines between two ESX hosts that store the virtual machine swap files in different locations, vCenter 4.0 may require enough disk space to store two full sized copies of the virtual machine swap file. This issue occurs if there is not enough space in the datastore.

For example, a virtual machine configured with 8 GB of memory and a 2 GB memory reservation requires a 6 GB swap file. If this virtual machine resided on an ESX host that stores swap files on local storage and was being migrated to an ESX host that stores swap files with on a shared Datastore, the operation may require twice the size of the swap file.

A vMotion might also fail due to lack of disk space if you are migrating a virtual machine between two ESX hosts that:

• Do not have an explicit host-local swap configuration (default)
• Have an explicit host-local swap location, pointing to the same datastore on both hosts (uncommon)

Resolution

This issue is resolved in VMware vCenter Server 4.0 Update 2, available at VMware Downloads. For more information, see the VMware vCenter Server 4.0 Update 2 Release Notes.

To resolve this issue, you must ensure that you have adequate amount of space on the datastores. To free up space, consider:

• Increasing capacity
• Moving virtual machines to other storage
• Adding additional datastores
• Removing old snapshots
• Cleaning up VMware VMFS

For more information about these operations, see Troubleshooting a datastore or VMFS volume that is full or near capacity (1003412).

Workaround

Since only the non-reserved memory uses the swap file, you can temporarily increase the memory reservation of the virtual machine to match the allocated memory while conducting the vMotion.

Additional Information

Troubleshooting a datastore or VMFS volume that is full or near capacity
vCenter Server 4.0 vMotion の操作が次のエラーで失敗する： Insufficient disk space on datastore