About reducing the size of VMware backups

Article:HOWTO70911  |  Created: 2012-02-08  |  Updated: 2013-10-02  |  Article URL http://www.symantec.com/docs/HOWTO70911
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About reducing the size of VMware backups

This topic applies to policy configuration for NetBackup for VMware.

NetBackup provides the following options for reducing the backup size for a VMware virtual machine:

Table: Options for reducing the virtual machine backup size



Block level incremental backup (BLIB)

BLIB reduces the size of backups (full and incremental) by tracking block-level changes. Only the blocks that have changed since the last full or incremental are included in the backup. For incremental backups, this option applies to cumulative and to differential backups.

BLIB works with VMware's Changed Block Tracking in vSphere to track block-level changes in the virtual machine.

The Enable block-level incremental backup option is enabled by default on the NetBackup policy VMware tab. NetBackup uses BLIB for storage optimization when the backup runs.


The first backup you run with BLIB must be a full backup.

See Block-level backup (BLIB): full vs incremental.


BLIB works only with ESX 4.0 or later virtual machines at version vmx-07 or later.


If you have used the vSphere Client interface to manually create a snapshot of the virtual machine and that snapshot is currently active, you may have to delete the snapshot.

See Deleting a vSphere Client snapshot.

Exclusion of deleted blocks.

Reduces the size of virtual machine backups by excluding any deleted sectors in the file system on the virtual machine.

To enable this option, click Exclude deleted blocks on the policy VMware tab.

Refer to Exclude deleted blocks in the following topic:

See Optimizations options (VMware).

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