Read the following information about the algorithm for snapshot cataloging for each array.
Snapshot Cataloging for Huawei and NetApp Storage Arrays
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The first full backup operation scans the entire CIFS share or NFS export to determine which files to catalog. Subsequent backup operations (including full, incremental, and differential backup operations), get the list of changed files from a file server without scanning the CIFS share or the NFS export.
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For the deferred catalog operation, full, incremental, and differential backup operations perform an incremental SnapDiff operation from the previously cataloged snapshot backup operation. If none of the previous snapshot backup operations are cataloged, then full backup operations perform a full scan, using the traditional scan method to determine which files to catalog.
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For the backup copy operation, if you run the snapshot backup operation with the Skip Catalog Phase for Snap Backup option, then the backup copy operation of a full backup operation performs a full scan operation. To determine which files to catalog, the backup copy operation (for both incremental backup operations and differential backup operations) performs the SnapDiff operation between the previous backup copied snapshot and the current snapshot.
Snapshot Cataloging for the Dell EMC Isilon/PowerScale, Hitachi NAS, and Dell EMC Unity Storage Arrays
All backups walk the CIFS shares or NFS exports to determine the files to catalog.