Snapshot files are present for a VM though vSphere's Snapshot Manager doesn't show any. An alert may be present indicating the VM has a "Snapshot > 100GB"

Products

• VMware vCenter Server
• VMware vSphere ESX 8.x

Issue/Introduction

If a snapshot file for a virtual machine (VM) grows larger than 100 GB, vSphere will display a red banner-style alert on the VM’s Summary page in the vSphere UI. This alert helps administrators identify snapshots consuming significant datastore space.

In the vSphere UI, select a VM and click on Snapshots to open the window showing any snapshots that are present and allowing the user to take new snapshots, revert to a previous snapshot, consolidate snapshot files, and so forth:


Even if Snapshot Manager shows no active snapshots, you can still confirm their presence by inspecting the VM’s folder directly:

1. Go to Storage in the vSphere Client.

2. Select the datastore where the VM resides.

3. Click Files, then navigate to the VM folder.

4. Look for .vmdk files with -00000X suffixes. These are snapshot delta disks.

Snapshot delta disks begin with the same base name as the original virtual disk. For example:

• Base disk: mydisk5.vmdk

• Snapshot disk: mydisk5-000001.vmdk

If any of these delta disks exceed 100 GB, vSphere will generate the alert to notify you that the snapshot is occupying substantial space. There may be additional errors or alerts present saying that Disk Consolidation is Needed or pointing out a backup failure or failed tasks related to snapshots.

 

Cause

Snapshot files can remain in a VM’s datastore even when no snapshots are visible in Snapshot Manager due to several underlying causes.

• One common scenario involves third-party backup solutions such as Veeam, which create temporary helper snapshots during backup operations. These snapshots are often managed outside of vSphere’s native snapshot tracking. If a backup job fails, is interrupted, or does not clean up properly, these helper snapshots can become "orphaned". This means the delta disk files (for example, *-000001.vmdk) still exist, but the snapshot metadata is missing from vCenter, so Snapshot Manager shows no active snapshots.
  
  
• In addition to backup-related orphaning, other conditions can lead to hidden snapshot files. Refer to article, Troubleshooting virtual machine snapshot descriptor problems, which shows how snapshots may not appear in Snapshot Manager if:

  • The VM configuration file (.vmx) is not properly updated during snapshot creation.

  • The snapshot descriptor file (.vmsd) is missing or corrupted.

  • The VM was restored or cloned from a backup that included snapshot delta disks but excluded metadata.

  • Manual file operations or storage migrations left behind snapshot files without proper registration.

 

Resolution

The scenarios described can result in a VM continuing to run on delta disks without any visible indication in the vSphere UI. This can lead to performance degradation, excessive datastore consumption, and inconsistencies during backup operations if not addressed. Consolidation is typically required to merge changes back into the base disk and remove orphaned snapshot files.

Users may attempt to resolve this by creating a new snapshot through Snapshot Manager and then selecting Delete All or Consolidate. While this approach can sometimes succeed, it frequently fails at one of those steps or appears to complete without actually removing the snapshot delta files from the datastore.

A more reliable method is to use Storage vMotion to migrate the VM’s storage to a different datastore. This process reads from any delta disks and writes out a clean base disk at the target location, effectively eliminating orphaned snapshot remnants. For guidance, refer to VMware’s documentation:

• How to Migrate Your Virtual Machine with Storage vMotion

• Troubleshooting virtual machine snapshot descriptor problems

• Cloning and converting virtual machine disks with vmkfstools - another option that might be useful if few disks have snapshots present on a larger VM with multiple disks.

These resources outline Storage vMotion and additional options for resolving snapshot-related issues and ensuring the VM is no longer dependent on delta disks.