Faster Incremental Backups for NAS File Servers Using NetApp SnapDiff


You can use SnapDiff for faster incremental backups for regular backups of NAS file servers (network shares). SnapDiff is a NetApp feature that identifies which files changed between snapshots, so that backups do not have to traverse the entire file system to determine which files changed.

On NetApp storage arrays, all IntelliSnap backups of network shares use SnapDiff. You can also use SnapDiff for regular backups of network shares.

SnapDiff is especially effective when you have a large number of files that do not change a lot between snapshots.

Note: Starting ONTAP 9.10.1, NetApp SnapDiff v1 and v2 are no longer supported. Once you upgrade to NetApp ONTAP >= 9.10.1, the first incremental scan will take longer as a TrueUp operation runs to gather file information. All the subsequent jobs will continue and use a recursive scan to collect file information.

How SnapDiff Works

The first full backup job creates a baseline snapshot. A snapshot is created, data is scanned by traversing the file system, a snapshot is created, and then data is backed up from the snapshot.

Subsequent backups are incremental. SnapDiff identifies the data that changed by comparing the previous and current snapshots, without traversing the file system. Data is then backed up from the snapshot.

At the end of each job, snapshots created by the previous job are deleted from the array, and only one set of snapshots is retained on the array.

The scan operation that traverses the file system is used only in these cases:

  • The snapshot from the previous job is not available

  • The snapshot creation fails in the current job

  • The SnapDiff operation fails