Block-level backup (BLIB): full vs incremental
This topic applies to policy configuration for NetBackup for VMware.
When you use the option in the policy, NetBackup uses VMware's Changed Block Tracking feature (CBT) to reduce the backup size.
This option reduces the size of full backups as well as the size of incremental backups, as follows.
Table: Block-level backup of the virtual machine: full vs incremental schedule
Type of backup | Optimization that is used in backup |
|---|---|
Backup of entire virtual machine, with full schedule | Backs up only the blocks that have changed since the .vmdk was created. Note that the blocks that are not initialized are excluded from the backup. |
Backup of entire virtual machine, with incremental schedule | Backs up only the blocks that have changed since the last backup, as follows:
Note: On incremental backups, the option backs up the changed files as well as their metadata. Note: VMware CBT may occasionally reset tracking of file changes in the virtual machine, such as after a power failure or hard shutdown. For the next backup, NetBackup reads all the data from the vmdk files and the backup takes longer than expected. If deduplication is enabled, the deduplication rate is lower than expected. The following VMware article contains more information on CBT: |
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