PowerScale OneFS Web Administration Guide

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Snapshot-based incremental backups

You can implement snapshot-based incremental backups to increase the speed at which these backups are performed.

During a snapshot-based incremental backup, OneFS checks the snapshot taken for the previous NDMP backup operation and compares it to a new snapshot. OneFS then backs up all files that was modified since the last snapshot was made.

Dell Technologies recommends snapshot-based incremental backup when the change rate is under 2%.

You can perform incremental backups without activating a SnapshotIQ license on the cluster. Although SnapshotIQ offers a number of useful features, it does not enhance snapshot capabilities in NDMP backup and recovery.

Set the BACKUP_MODE environment variable to SNAPSHOT to enable snapshot-based incremental backups and ensure that the DMA is sending the correct BASE_DATE and BACKUP_OPTIONS. If you enable snapshot-based incremental backups, OneFS retains each snapshot taken for NDMP backups until a new backup of the same or lower level is performed. However, if you do not enable snapshot-based incremental backups, OneFS automatically deletes each snapshot generated after the corresponding backup is completed or canceled.

NOTE A snapshot-based incremental backup shares the dumpdates entries in dumpdates database along with the other level-based backups. Therefore, make sure that you do not run snapshot-based backups and regular level-based backups in the same backup paths. For example, make sure that you do not run a level 0 backup and snapshot-based incremental backup in the same backup path or vice versa.

After setting the BACKUP_MODE environment variable, snapshot-based incremental backup works with certain data management applications (DMAs) as listed in the next table.

Table 1. DMA support for snapshot-based incremental backups
DMA	DMA-integrated
Generic	Enabled only through an environment variable.
Bakbone	Enabled only through an environment variable.
CommVault	Enabled only through a cluster-based environment variable.
DellEMC	Enabled only through an environment variable.
Symantec	Enabled only through an environment variable.
Tivoli	Enabled only through a cluster-based environment variable.
Symantec NetBackup	Enabled only through a cluster-based environment variable.
Symantec Backup Exec	Enabled only through a cluster-based environment variable.