Dell Unity™ Family VNX® Series Data Import to Unity All Flash or Hybrid, or UnityVSA™ System User Guide

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Preserving stub files

If you are using the CIFS protocol, you can preserve stub files as stub files when you import from a VNX source to a Unity destination. Preserving stub files lessens the workload when migrating data from VNX to Unity systems.

Prerequisites

Cloud Tiering Appliance (CTA) must be configured on the source VNX system. CTA must be set for file archive. If CTA is configured on the source VNX system and a VDM import to Unity is run, all files on the associated file system are imported as regular files. However, you can specify that stub files be preserved as stub files when they are migrated to the destination Unity system.

You must have the following in place to preserve stub files that are migrated from VNX to Unity systems:

  • A VDM on the source VNX system
  • A file system and CIFS share on the VNX system
  • CTA configured on the file system for archive
NOTE: This operation can only be performed using the CLI.

Steps

  1. Enter the dhsmEnabled parameter on the Unity system to enable the stub preservation feature: svc_nas ALL -param -facility imt -modify dhsmEnabled -value 1
    The value 1 is set after reboot.
  2. Run the following VNX command against all source file systems that contain DHSM stubs that you want to preserve after migration: fs_dhsm -modify fsname -backup offline
    For more information about the VNX command, see the VNX Command Line Interface Reference for File.
  3. Set up the remote CIFS migration between the VNX and Unity systems, and create the import session.
  4. After the migration cutover phase is finished, map the CIFS share on the Unity side and verify that the stub files have been migrated.
  5. Commit the import session.
  6. Configure CTA on the Unity system if you want stub files to be archived there.

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