By Alison / Last Updated September 5, 2022

Error: VMware Virtual machine disk consolidation is needed

Sometimes you may see a warning “virtual machine disks consolidation is needed” in the console of Vmware vSphere 5, 6.5, 6.7, etc. It is usually reported in the Summary tab of a VM, indicating that the snapshot deletion process is not completed successfully.

virtual machine disk consolidation is needed

When you delete a snapshot, virtual machine disk consolidation should occur along with the deletion operation. But sometimes you may incorrectly delete a VM snapshot (due to various reasons), causing the snapshot VMDK files or logs to remain on the datastore. As a result, the virtual machine cannot be backed up.

In this article, I will analyze what possible reasons lead to this error, and provide 2 proven ways to resolve it.

This article covers:

What is virtual machine disk consolidation and why is it necessary

In general, virtual disk consolidation is a process of merging snapshots into the original virtual machine.

Taking a VMware snapshot will make the original virtual disk file read-only, and create a delta disk file to store all changes made to the VM afterwards. The more and longer snapshots are kept, the more redundant data becomes, thus taking up more disk space and even affecting the performance of the original virtual machine.

Therefore, virtual machine disk consolidation is needed to merge snapshots and remove redundant data.

disk consolidation

To do it, you just need to delete VMware snapshots properly via Snapshot Manager - this will merge them to the original virtual disk. But if you delete snapshots incorrectly, things can be dangerous.

Therefore, we can say the underlying reason for the virtual machine disk consolidation needed warning is usually an incomplete snapshot deletion caused by incorrect operation. And the way to get rid of that warning is to do the disk consolidation properly.

image.png If you accidentally delete the descriptor files, it's still possible to recover deleted VMware snapshot. But if the snapshot data files are deleted directly, it may result in severe data loss. So please be careful when performing such operations.

Other reasons that may lead to disk consolidation failure

Except for incorrect operations, there are some other reasons that may cause a snapshot deletion fails to complete successfully. So before trying to performing disk consilidation, please check the following points to exclude any possible interference:

  • Connection issues between the ESXi host and vCenter server.
  • Poor storage performance, large or timeout snapshots may not be successfully deleted.
  • Lack of VMFS disk space for consolidating the snapshot and the original virtual disk. If the free space on the datastore is less than 1 GB, this error may occur.
  • Snapshot files are locked, for example, you cannot successfully delete the snapshot while a third-party software is backing up the VM.
  • Backup vProxy VM, as the VM disk is part of the proxy VM and is not released after the backup completes. To fix this, check the last backup attribute of the VM in "Custom Attributes", note down the vProxy server and go to the vProxy VM, select Edit Settings and identify the virtual disk allocated in the vProxy VM from the affected VM, then remove it from VM settings (not delete from storage), then you may perform disk consolidation normally.

remove vproxy vm disk

2 ways to resolve virtual machine disk consolidation is needed

To solve the VMware virtual machine disk consolidation is needed error, you just need to perform disk consolidation properly after ruling out the above possible factors.

In this section, I will introduce 2 proven ways of how to do virtual machine disk consolidation.

Way 1. Manually consolidate virtual disks via VMware ESXi web client

1. Access to VMware ESXi web client, and navigate to Virtual Machines from the left inventory.

2. Right-click on the VM name and select Snapshots > Consolidate disks.

Perform disk consolidation on web client

3. Click Yes to confirm disk consolidation of the VM.


Way 2. Using PowerCLI to perform VMware VM disk consolidation

1. Connect to vCenter server and provide relevant credentials:

Connect-VIServer -Server [server name] -Protocol [http] -User [user name] -Password [password]

2. Check which VM needs disk consolidation:

Get-VM | Where-Object {$_.Extensiondata.Runtime.ConsolidationNeeded}

3. Consolidate the disk of a specific virtual machine called MyVM:

(Get-VM -Name "MyVM").ExtensionData.ConsolidateVMDisks()

Tip: To consolidate all virtual machines that need disk consolidation:
Get-VM | Where-Object {$_.Extensiondata.Runtime.ConsolidationNeeded} | foreach {$_.ExtensionData.ConsolidateVMDisks_Task()}

Use VMware snapshot properly to avoid various issues | 3 tips

As you can see, using VMware snapshots incorrectly may result in errors, and keeping snapshots in the long run can have a negative impact on the performance of VM systems. So for better working with VMware snapshots, here I summarized 3 best practices.

Tip 1. Do not use VMware snapshots as backups

It is commonly accepted that VM snapshot and backup cannot replace each other. Snapshots depend on the parent disk, if the parent disks are deleted, the snapshot files are not sufficient to restore a VM.

But VM backup is an independent copy of the VM, it can be safely stored offsite, to the cloud, or other locations. Restore from it you will gain an instant usable VM.

VM Snapshot vs Backup

Tip 2. Use only 2-3 snapshots for each VM

Actually, maximum of 32 snapshots are supported in a chain. However, the more snapshots you kept, the more they affect the VM performance.

Therefore, for a better performance please use only 2 to 3 snapshots.

Tip 3. Do not use a single snapshot for more than 72 hours

For most times, you need to reserve 20-30% extra storage for a single snapshot. The longer you keep these snapshots, they will take more disk space and thus affect the performance of your VM.

It is recommended by VMware that do not to keep snapshots for more than 72 hours. Therefore, it is necessary to delete the snapshots in time to merge the changes to the parent disk when they are no longer useful, or before creating backups of your VM.

Free backup software to protect your VMs from manual errors

Just like the VMware virtual machine disk consolidation is needed error, manually backup VMware VMs may also result in many other errors. Therefore, to avoid manual errors, many IT staffs turn to dedicated backup tools that can backup VMs automatically.

Here I recommend you AOMEI Cyber Backup, the free VMware backup software for the following benefits:

Auto Execution: capable of backing up multiple VMs automatically based on daily, weekly, monthly schedule.
Role Assignment: allows one administrator to create sub-accounts with limited privileges, effectively avoid errors caused by others’ mis-operations.
Restore from Any Point: capable of restoring the entire VM from any created history backup versions.
Perpetual Free Edition: you can also use this free version to protect your VMs with on time limit.

In next section I will demonstrate how to create an automatic backup task of multiple ESXi VMs. You can click the following button to enjoy the freeware:

Download FreewareVMware ESXi & Hyper-V
Secure Download

*You can choose to install this VM backup software on either Windows or Linux system.

3 easy steps to create automatic backup tasks of multiple VMs

1. Bind Devices: Access to AOMEI Cyber Backup web client, navigate to Source Device > VMware ESXi > + Add VMware ESXi to add a host. And then click > Bind Device.

Tip: Except for VMware ESXi 6.0 and all later versions, it also supports Hyper-V on Windows Server 2012 and all later versions.

Add VMware ESXi host

2. Create Backup Task: Navigate to Backup Task > + Create New Task, and then set Task Name, Backup Type, Device, Target, Schedule, and Cleanup.

  • Device: using AOMEI Cyber Backup you can backup multiple, or even all VMs on the host at once.
  • Target: You can select to back up to a local path, or to a network path. Used paths will be saved in Favorite Storage for handy selection.
  • Schedule: You can choose to perform full, differential or incremental backup, and automate execution daily, weekly or monthly according to the frequency you specified.
  • Cleanup*: You can specify a retention period, and the old backup files that exceed the period will be automatically deleted. This is an advanced feature.

3. Start Backup: You can select Add the schedule and start backup now, or Add the schedule only.

Create a VMware ESXi backup task

Created backup tasks will be listed and monitored separately, for progress checking and schedule changing.

Restore VMware ESXi VM to new location


The VMware virtual machine disk consolidation is needed error is commonly caused by incomplete of snapshot deletion. To fix this, I introduced 2 methods of how to do virtual machine disk consolidation in VMware in this article.

Just like large VMware snapshot size can result in performance degradation, incorrect snapshot deletion can even cause data loss. Therefore, I also summarized 3 best practices for using snapshots. If you want to further protect your VM data from accidental mis-operations, especially from manual errors, some professional backup software may be very helpful.