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NetVault Plug-in for VMware 12.3 - User Guide

Introducing NetVault Backup Plug-in for VMware Installing the plug-in Configuring the plug-in Defining a backup strategy Using the image-level backup method Using the file-level backup method Restoring image-level backups Restoring file-level backups Troubleshooting

About CBT

The VMware Changed Block Tracking (CBT) feature allows virtual machines to track changed disk sectors. When CBT is enabled on a virtual machine, a “Change ID” is assigned to each disk when a snapshot is generated for backups. The Change ID identifies the state of a virtual drive at a specific point in time. Subsequent snapshots capture only the blocks that have changed since the last snapshot.

CBT offers the following advantages:

•
It allows Incremental and Differential image-level backups of virtual machines.
•
It often reduces the backup size of Full image-level backups because only the used sectors of a virtual drive are backed up.

CBT is only supported on virtual machines that use virtual hardware 7 or later. CBT is not supported on virtual machines that use Physical compatibility RDM virtual drives, Virtual compatibility RDM (Independent Disks), or virtual drives attached to a shared virtual SCSI bus.

Enabling CBT on individual virtual machines

By default, CBT is disabled on a virtual machine. If you want to perform Incremental or Differential Backups of virtual machines, you must enable CBT for the Full Backup that serves as the base backup for subsequent Incremental and Differential Backups.

The Plug‑in for VMware provides the following methods to enable CBT on virtual machines:

•
Enable CBT on specific virtual machines: To enable CBT on specific virtual machines, you can use the Enable Change Block Tracking method, which can be accessed from the from the context menu for the plug-in on the NetVault Backup Selections page. This section describes the procedure for enabling CBT on individual virtual machines.
•
Enable CBT on all virtual machines included in a backup: To enable tracking automatically on all virtual machines that are included in a backup job, you can set the backup option “Enable Changed Block Tracking for VM. For more information, see Enable Change Block Tracking for VM.
To enable CBT on a virtual machine:
1
Start the Backup Job Wizard, and click Create New next to the Selections list.
2
Open the NetVault Backup Client on which plug-in is installed, and then open VMware Plugin.
3
Open the ESXi or vCenter Server and the other applicable container nodes — for example, Datacenter, Cluster, Resource Pool, and other nodes — to display the target virtual machine.
4
Click the virtual machine, and select Enable Change Block Tracking from the context menu.
This option is available to only those virtual machines on which CBT is disabled.
5
After the virtual machine is reconfigured, a message is displayed. To close the dialog box, click OK.
Important notes
•
To create the first Full Backup of a virtual machine with Changed Block Tracking enabled, the target virtual machine must be turned off to enable CBT. For more information, see http://kb.vmware.com/kb/1031873.
The virtual machine can be restarted when the backup job starts transferring data. During subsequent Full, Incremental, or Differential Backups, the virtual machine can remain turned on.
•
At the time of enabling CBT, no snapshots should exist on the target virtual machine. For more information, see http://kb.vmware.com/kb/1033816.
•
The reconfiguration of Changed Block Tracking takes effect only after the virtual machine goes through a stun and unstun cycle. This cycle includes power-on, resume after suspend, migrate, or snapshot create, delete, or revert operations.
•
After you enable CBT for a virtual machine, all subsequent Full, Incremental, and Differential Backups are performed as CBT-based backups for that virtual machine. You do not have to enable CBT for each job.

Disabling CBT on a virtual machine

After you enable CBT on a virtual machine, all subsequent Full, Incremental, and Differential Backups are performed as CBT-based backups for that virtual machine. To stop using CBT, you must disable this feature.

1
Start the Backup Job Wizard, and click Create New next to the Selections list.
2
Open the NetVault Backup Client on which plug-in is installed, and then open VMware Plugin.
3
Open the ESXi or vCenter Server and the other applicable container nodes — for example, Datacenter, Cluster, Resource Pool, and other nodes — to display the target virtual machine.
4
Click the virtual machine, and select Disable Change Block Tracking from the context menu.
This option is available to only those virtual machines on which CBT is enabled.
5
After the virtual machine is reconfigured, a message is displayed. To close the dialog box, click OK.

Manually disabling CBT on a virtual machine

To manually disable CBT on a virtual machine, use the following procedure.

1
Turn off the virtual machine.
2
In the virtual machine's configuration (“.vmx”) file, edit the following entry and set it to False:
ctkEnabled = “False”
3
In the “.vmx” file for each virtual drive, edit the following entry and set it to False:
scsix:x.ctkEnabled = “False”
4
Create and delete a snapshot for the virtual machine to complete a stun and unstun cycle.
The “.ctk” files for the virtual machine are automatically deleted when you turn on the virtual machine.
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