Troubleshooting › Virtual Machine Backup and Restore Related › File System Catalog Job Fails or Recovery Point Check Fails for Host-Based Agentless Backup

File System Catalog Job Fails or Recovery Point Check Fails for Host-Based Agentless Backup

Valid on Windows platforms. Valid for VMware VM only.

Symptom

• File system catalog job fails for host-based agentless backup recovery points
• Recovery Point Check fails during host-based agentless backup job and the next Incremental backup gets converted to a Verify backup.

Solution

This may be caused by a known issue of VMware (see the VMware KB article). When you quiesce a VMware VM, the snapshot contains corrupted data. The backup reads data from the snapshot and the data that is backed up also becomes corrupted.

Note: This problem occurs with all VMware ESXi versions and on a VM with guest OS running Windows 2008 R2 SP1 and Windows 2012. Arcserve UDP cannot detect the data corruption problem because VMware does not return an error in such cases. You may not be aware of the problem until you try to restore data.

You can follow the Arcserve KB article to check whether the problem is caused by this VMware known issue. The workaround recommended by VMware is to disable the VSS writers, such as MSSearch Service Writer (ignore it, if not installed) and Shadow Copy Optimization Writer (typically present in every Windows VM), in guest OS of VM. You can manually disable the writers per the VMware KB article.

Arcserve UDP also provides a simple way to disable the writers, if VMware Tools snapshot quiescing method is used. Follow these steps to disable the writers.

At Proxy Server level (applicable for VMs protected by this proxy server)

1. Log in to the proxy server.
2. Open the registry key from the following location:

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

3. Create a Multiple-String value with the name DisableSpecificVSSwriters.
4. Enter the names of the VSS writer that is expected to be disabled (each writer name occupies one line).
5. Save the registry key.

At VM level

1. Log in to the proxy server.
2. Open the registry key from the following location:

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

3. Create a Multiple-String value with the name DisableSpecificVSSwriters.
4. Enter the names of the VSS writer that is expected to be disabled (each writer name occupies one line).
5. Save the registry key.

Notes:

• If you add the registry key in the VM and proxy level registry both, then the setting in the VM level registry will have the priority over the setting in the Proxy level registry.
• This registry setting works only when the VMware Tools snapshot quiescing method is used in the backup plan.
• If you have ever configured writers manually in the guest OS of the VM per the VMware KB article, your configuration will be overwritten.
• The name of the writer is case sensitive and must be an exact match as shown in the output of “vssadmin list writers”.
• If you want to enable all writers again, do not delete the registry value DisableSpecificVSSwriters. Instead, retain the registry value but remove the content within the registry. If DisableSpecificVSSwriters does not exist, Arcserve UDP assumes that nothing needs to be changed in terms of enabling or disabling VSS writers.