Troubleshooting › UDP Agentless Backup Fails in VMware ESXi 6.0

UDP Agentless Backup Fails in VMware ESXi 6.0

Symptom

Arcserve UDP agentless backups may fail when you attempt to back up a virtual machine in VMware ESXi 6.0 and if the Change Block Tracking (CBT) function is enabled.

This is a known issue of VMware. When the backup fails, the following two  behaviors can occur:

• Arcserve UDP may not connect to the CBT function of the ESXi host. As a result, Arcserve UDP cannot receive the used or changed data block information from the virtual machine.
• Arcserve UDP may fail to capture the quiesced snapshots of the virtual machine. (This can occur every time Arcserve UDP captures a snapshot or when you manually capture a snapshot in the vSphere client.)

Solution

VMware has resolved this issue in their latest build, ESXi 6.0 Build 2715440. You can install the ESXi600-201505001 patch to resolve this issue. For more information about downloading and installing the patch, see the VMware KB article.

If you cannot apply the patch, you can resolve the issue by making the following changes in the registry key:

Solution for CBT connection failure.

If Arcserve UDP cannot connect to CBT, then instead of failing the backup job, Arcserve UDP can continue the backup job. However, instead of performing an incremental backup, by default Arcserve UDP will perform a complete disk backup of the VM. If you do not want to perform a full backup automatically, you can add a registry key to change this default behavior. If you add the key and set the value to 1, then Arcserve UDP will fail the backup job when a CBT error occurs.

You can add this registry key in the Proxy server as follows:

At Proxy Server level (applicable for all backup jobs running in this proxy server)

1. Open the registry key from the following location:

   [HKEY_LOCAL_MACHINE\SOFTWARE\Arcserve\Unified Data Protection\Engine\AFBackupDll]
   

2.  Enter the following dword:

   "BackupEntireDiskOnCBTBitmapFailure"=dword:00000001
   

3. Save the registry key.

At VM level

1. Open the registry key from the following location:

   [HKEY_LOCAL_MACHINE\SOFTWARE\Arcserve\Unified Data Protection\Engine\AFBackupDll\<vm instance uuid>]
   

2. Enter the following dword:

   "BackupEntireDiskOnCBTBitmapFailure"=dword:00000001
   

3. Save the registry key.

Solution for quiesced snapshot failure

Ensure that Take crash-consistent snapshot if application-consistent snapshot fails option is selected on the Source tab of the Host-Based Agentless backup plan.

Note: If you add the registry key in both the VM and proxy level registry, then the setting in the VM level registry will have the priority over the setting in the Proxy level registry.