Backup in SAN transport mode fails for virtual machine with virtual RDMs: Timeout waiting for VixDiskLibThread operation, possible VDDK Deadlock encountered

To use SAN transport for a VM with virtual RDM disks, perform a crash-consistent backup.

Symptoms

When using SAN transport mode to back up a virtual machine that contains virtual RDM disks, the backup fails.

The vsbkp.log file indicates that the operation is timing out during the connection to the disk:

CVMDiskInfo::WaitForVixDiskLibThread() - Timeout waiting for VixDiskLibThread operation, possible VDDK Deadlock encountered

Causes

When performing an application-consistent backup by using SAN transport mode, the operation generates a large number of Map Disk Region events on the vCenter. With virtual RDM disks, the connection to the virtual disk takes a long time and times out, causing the backup to fail.

Resolution

To resolve this issue, configure a subclient to perform a crash-consistent backup for the virtual machine that uses SAN transport:

1. From the CommCell Browser, expand Client Computers > virtualization_client > Virtual Server > VMware.
2. Right-click the backup set and click New Subclient.
3. On the General tab, enter the subclient name.
4. From the Transport Mode for VMware list, select SAN.
5. On the Backup Options tab, clear the Quiesce Guest File System and Applications check box.
6. Click OK.
7. Right-click the subclient and select Backup.
8. In the Backup Options dialog box, select Full, and click OK to run an immediate full backup.