Introducing Arcserve Backup Agents and Options › Using Agents › Agent for Virtual Machines › Troubleshooting › Backup and Recovery Operations › Failed to Create Disk Bitmap Errors Occur During Backups

Failed to Create Disk Bitmap Errors Occur During Backups

Valid on Windows platforms.

Symptom

One of the following messages appear in the Activity Log after a virtual machine backup job runs:

AW0720: Failed to create the disk bitmap for the disk x:\VmMountDir\VM\xxxx.vmdk, "Full disk including unused blocks will be backed up."

AW0589: Failed to enable changed block tracking for the virtual machine, "Full disk including unused blocks will be backed up." 

Solution

The backup jobs fail when Arcserve Backup cannot identify the blocks of data that changed. The following items are required for changed block tracking (CBT) to detect disk sectors that are in use with the special character "*" change ID.

• The virtual disk must reside on a virtual machine file system volume and was backed up by the SAN, an iSCSI device, or a local disk

  Note: Raw device mappings (RDM) are not a virtual machine file system.

• The virtual machine must contain zero (0) snapshots when CBT is enabled.

Note: Under some conditions, such as a power failure or a hard shutdown of the virtual machine, CBT may reset and lose track of the incremental changes.

To correct this behavior, do the following:

1. Delete all of the snapshots on the affected virtual machine.
2. Shut down the virtual machine.
3. Open the vCenter Client or the vSphere Client.
4. Locate the affected virtual machine. Right-click the virtual machine and click Edit Settings on the pop-up menu to open the Virtual Machine Properties dialog.
5. In the Advanced section, click General, then click Configuration Parameters to open the Configuration Parameters dialog.

   

6. From the Configuration Parameters dialog, set all of the disk device ctkEnabled properties to false. For example, ctkEnabled, ide0:0ctkEnabled, ide0:1ctkEnabled, scsi0:0.ctkEnabled, scsi0:1.ctkEnabled, and so on, as illustrated by the following dialog.

   Note: You should also change the value to false for all of the disk devices for the virtual machine.

   

7. Click OK to save the changes and close the Configuration Parameters dialog. Then click OK to close the Virtual Machine Properties dialog.
8. Open the data source folders on the virtual machine and delete all of the –ctk.vmdk files.
9. Power on the virtual machine.

After you complete these steps, CBT will be enabled and the .ctk.vmdk files will be recreated after the backup job runs.