NetApp's ONTAP SnapDiff 2 is going away soon, so in NetBackup release 10.3 we updated NetBackup to SnapDiff version 3. SnapDiff is an ONTAP feature that can identify the differences between two snapshots of a file system. Some or all of the files or folders in the differences can then be selected and restored. Our use of SnapDiff 3 allows indexing the file/folder structure from NetApp snapshots.
Previously, NetBackup supported indexing from NetApp snapshots by mounting a snapshot and then "traversing" (mounting and recursively analyzing) the snapshot's filesystems. NetBackup collected current file/folder metadata for full backups, or changed metadata for incrementals. However, crawling does not leverage SnapDiff's difference engine, or vendor change tracking (VCT) to collect the metadata from snapshots more quickly using information already available on the filer.
The NetBackup 10.3+ Snapshot Manager (NBSM) now uses SnapDiff VCT to collect file metadata as well. When an index from snapshot operation is needed, NetBackup determines how the snapshot was produced and whether VCT can be used to gather file/folder metadata. If VCT can be used, an index from snapshot will give an incremental view for incremental schedules and a full view for full schedule. The first index for a full backup will generate a traversal-based index. For subsequent fulls, NetBackup will use VCT information and generate a synthetic full view speeding up view generation.
VCT indexing will be enabled for all VCT-supported plugins. All other plugin indexing will continue to use the traversing method.
NetBackup customers with NetApp filers should upgrade to 10.3 ASAP for this big improvement in SnapDiff performance.
