Backup server hangs while performing GRT based AVVI backups of Virtual Machines to a Deduplication Folder.


Backup server goes in to a hang (freeze) while performing Granular Recovery Technology (GRT) based AVVI  backups of Virtual Machines to a Deduplication Folder


This problem can occur while backing up larger Virtual Machines (around and above 1TB). The problem comes from the repeated open/close calls using PDVFS (Pure Disk Virtual File System Service) that has to be made when reading the large size VMDK's.



Solution (for Windows 2012 R2 and Windows 8.1 only)
Apply the Microsft Update discussed in KB308664 which at the time of writing this article was available at:

Solution (other affected operating systems)
As the Microsoft fix only applies to Windows 2012 R2 and 8.1, there will be no programmatic fix for older operating systems. Backup Exec 2014 Service Pack1 (and later versions) provides a workaround for this Microsoft issue. After ensuring you are running 2014 SP1 or later, then please execute the steps listed below.


Warning: Incorrect use of the Windows registry editor may prevent the operating system from functioning properly. Great care should be taken when making changes to a Windows registry. Registry modifications should only be carried-out by persons experienced in the use of the registry editor application. It is recommended that a complete backup of the registry and workstation be made prior to making any registry changes.

1)   On the Backup Exec server, enable the following registry value (Use VMDK Remote Mount =1):

      Key location:  HKEY_LOCAL_MACHINE\SOFTWARE\Symantec\Backup Exec For Windows\Backup Exec\Engine\VMware Agent 

      DWORD value:  Use VMDK Remote Mount

      Set the value to 1.

2)   Create or edit the existing backup job for the VMWare guest machines to DISABLE the Delayed Catalog  feature.  In the edit job options, under ‘Delayed Catalog’ tab, choose ‘Do not run a delayed catalog operation’.


NOTE:  A GRT related warning will be displayed in the backup sets for Virtual Machines (figure 1) if delayed catalog setting was NOT disabled after creating the above mentioned registry value, however this will not have any impact on GRT restores from the backup set.

Figure 1:







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