Troubleshooting the VMware Consolidated Backup error Backup snapshot already exists

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

• When performing a backup using Consolidated Backup of a virtual machine, the following error occurs:
  [YYYY-MM-DD HH:MM:SS.mmm 'vcbMounter' 3076440192 error] Error: Backup snapshot already exists.
  
• Snapshot manager for the virtual machine contains a snapshot called:
  
  • _VCB-BACKUP_
    
  • Consolidated Helper

Environment

VMware vCenter Server 4.0.x
VMware Consolidated Backup 1.0.x
VMware Consolidated Backup 1.1.x
VMware Consolidated Backup 1.5.x
VMware ESX Server 3.0.x
VMware vCenter Server 4.1.x
VMware VirtualCenter 2.0.x

Resolution

The previous backup failed to commit/delete the snapshot, leaving behind an entry in snapshot manager called _VCB-BACKUP_ or Consolidated Helper . The entry needs to be removed.

To remove the entry:

1. Log in to the Virtual Infrastructure Client
2. Right-click on the name of the virtual machine.
3. Click Snapshot.
4. Click Snapshot Manager.
5. Select _VCB-BACKUP_ or Consolidated Helper (whichever applies).
6. Click Delete.

If the snapshot manager does not list snapshots, follow the steps provided in Committing snapshots when there are no snapshot entries in the snapshot manager (1002310) to remove snapshots left behind by VCB.

Note: If the snapshot has been there for a while, it may be fairly large and may take a while to commit. You can browse the datastore that has the virtual machine to check the size of the -delta files. Occasionally the snapshot commit may appear as though as it has timed out. Typically, this occurs when VirtualCenter times out while monitoring the commit process which may have continued to complete successfully.

To increase the timeout value in VirtualCenter:

1. Start the VMware Infrastructure Client and connect to your VirtualCenter server.
2. Click Edit > Client Settings.
3. Select Use a custom value from the Remote Command Timeout section.
4. Change the value of Timeout in seconds: to 600
5. Click OK and save the changes.

After these snapshots have been deleted, Consolidated Backup proceeds past that checkpoint and performs the backup as normal.