VM snapshot needs consolidation

When a snapshot didn’t commit properly, it can happen that the snapshot manager in the vCenter server shows no snapshot(s), but that there are still active delta files on the datastore. These ‘hidden’ snapshot can cause the datastore to run out of space.

To report these ‘hidden’ snapshots (prior vSphere 5), I created a script that searches all the datastores  for ‘*.delta’ files and reported them by mail.

In vSphere 5 you have a new feature that reports and make it possible to consolidate these  ‘hidden’ snapshot(s). In vSphere 5 you get  a warning ‘Virtual machine disks consolidation is needed’ when the virtual machine snapshot consolidation has failed.


The snapshot manager shows no snapshots but there are delta files present on the datastore(s).

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In the vCenter server on the Virtual Machines tab you can enable the field “Needs Consolidation” to filter all the VMs that needs consolidation.


To consolidate the snapshot, right-click the virtual machine and choose Snapshot Consolidate.


Confirm the consolidate


Check the datastore and all the delta files are consolidated



With PowerCLI you can use the following one liner to list all the VMs that needs consolidation (thanks to Luc Dekens ):

Get-VM | where {$_.ExtensionData.Runtime.consolidationNeeded} | Select Name 


2 thoughts on “VM snapshot needs consolidation”

  1. Timely post. Thanks. I had some jobs that were creating some of these hidden snapshots on two VMs (Win2008 R2). They were piling up on me even when the snapshot manager (or even RVTools) showed no snapshots.

  2. Nice post, especially the CLI at the end. However i had a querry here regarding the delta files getting created. I confirm that never i have created snapshots for the VM. But i see few delta files with naming conventions of 000001.vmdk, 000002.vmdk, etc, present in the datastore. If any backup app has created them, then these files should have been deleted post successfull backup. Is there a possibility of delta files not getting deleted if the backup is unsuccessfull?

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