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  1. Home
  3. NetBackup™ NAS Administrator's Guide
  5. Section II. Using NAS-Data-Protection (D-NAS)
  7. Using Vendor Change Tracking
  9. Using VCT for indexing
NetBackup™ NAS Administrator's Guide

Using VCT for indexing

When Vendor Change Tracking (VCT) is enabled for a D-NAS policy, NetBackup does not perform any file system traversal for indexing a NAS volume. Instead, NetBackup uses the change list from the difference engine of the storage array to perform indexing of files and directories.

D-NAS policy supports the VCT-enabled index backups for NetApp, Dell EMC PowerScale (Isilon), Nutanix Files, and Qumulo NAS arrays.

Consider the following before using the index from snapshot with VCT for D-NAS policy:

  • Index job for the first full schedule:

    • When the index from snapshot for the first full schedule runs for a NAS volume. Then, NetBackup performs the file system traversal and generates an image catalog file.

    • File system traversal happens as the array vendors do not have any previous snapshot to get the change list.

  • Index job for the subsequent full schedule using VCT:

    • When VCT is enabled in the policy and a subsequent full schedule is run, NetBackup uses the following:

      • Previous full image catalog.

      • change list provided by the array vendor's difference engine from NBSM.

    • Using the previous catalogs, a synthetic catalog is created for the subsequent full schedule.

    • If number of streams per volume is changed from the last successful full index from snapshot, then NetBackup performs a file system traversal.

  • Index job for an incremental schedule using VCT:

    When VCT is enabled in the policy and incremental schedule runs:

    • Differential incremental schedule: The change list is identified using the current snapshot and the snapshot of the last successful index job.

    • Cumulative incremental schedule: The change list is identified using the current snapshot and the snapshot of the last successful full index job.

  • Following are the file entries that are added to the image catalog for index operation as per the schedule:

    • Full schedule: The full set of files.

    • Differential incremental schedule: Files that are added or modified after the last index job run for any schedule.

    • Cumulative incremental schedule: Files that are added or modified after the index job run for the last full schedule.

  • For a VCT-enabled D-NAS policy, the Snapshot or Replication retention period in SLP must be greater than the policy's schedule frequency.

  • VCT is not applicable if the base snapshot is not available.

  • The expiration period of the previous full and subsequent incremental snapshots is postponed until the next full schedule is completed.

  • For non-VCT supported arrays, the index job continues to use mount and file system crawl method.

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