About MSDP storage rebasing
During an initial backup, NetBackup writes the data segments from a backup to as few container files as possible. Read performance is best when the data segments from a client backup are close to each other on deduplication storage. NetBackup consumes less time finding and reassembling backed up files when their segments are near each other.
However, the data segments in a backup may become scattered across the disk storage each time the client is backed up. Such scattering is a normal consequence of deduplication.
NetBackup includes a process, called rebasing, that helps to maintain the data segments in as few container files as possible. Rebasing improves performance for the operations that read from the storage, such as restores and duplications. NetBackup writes all of the data segments from a backup into new container files even though the segments exist on storage already. Future backups then refer to the new copies of those segments rather than the old copies until any changes because of future rebasing. Deduplication rates for the backup jobs that perform rebasing are lower than for the jobs that do not rebase the data.
After the rebasing, NetBackup reclaims the storage space that the rebased data segments used.
Table: Types of rebasing describes the rebasing operations.
Table: Types of rebasing
Type | Description |
|---|---|
|
Normal backup rebasing |
The rebasing that occurs during a backup if the normal rebasing criteria are met, as follows:
Backup rebasing occurs only for the full backups that pass through the normal MSDP backup process. For example, the NetBackup Accelerator backups do not pass through the MSDP backup process. NetBackup reports backup job completion after the rebasing is completed. |
|
Periodic backup rebasing |
The rebasing that occurs during a backup if the periodic rebasing criteria are met, as follows:
Backup rebasing occurs only for the full backups that pass through the normal MSDP backup process. For example, the NetBackup Accelerator backups do not pass through the MSDP backup process. NetBackup reports backup job completion after the rebasing is completed. |
|
Server-side rebasing |
The storage rebasing that occurs on the server if the rebasing criteria are met. Server-side rebasing includes the deduplicated data that does not pass through the normal MSDP backup process. For example, the NetBackup Accelerator backups do not pass through the MSDP backup process. Some parameters in the |