9.8 Guidelines for Using DFS and Dynamic Storage Technology

The Dynamic Storage Technology coexists with DFS, but they are not tightly integrated. Use the guidelines in this section when using DST and DFS in the same environment.

9.8.1 DFS and DST Compatibility

NSS volumes that are shadowed with DST recognize DFS junctions on the primary volume. It does not migrate junctions to the secondary volume. Junctions work properly on a volume where DST is running. DFS junctions can point only to the primary volume of the shadow pair.

DST considers only the junction itself as data on the primary volume. It does not follow the junction to manage any data stored in the target location. You must manage the data in the target location independently of the junction’s volume, as you normally do for DFS junctions.

9.8.2 Using DFS Junctions in a DST Shadow Volume

When using Dynamic Storage Technology in combination with Distributed File Services, consider the following guidelines:

  • The shadowing efforts for the junction volume and the junction target volume are unrelated, and are not coordinated.

  • Create new DFS junctions only on the primary volume of a shadow relationship between two NSS volumes.

  • When the junction target volume is in a shadow relationship, point the junction at the primary volume. Junctions support only NSS volumes or NCP volumes as junction targets.

  • When the target volume of an existing junction becomes the secondary volume in a shadow relationship, the junction is broken. You must create a new junction that points to the same location on the primary volume of that shadow relationship, then delete the junction on the secondary volume.

  • Do not create a shadow relationship for any NSS volume while a DFS Move Volume or Split Volume is in progress for the volumes involved.

9.8.3 Moving and Splitting Volumes in a DST Shadow Volume

The DFS Move Volume and Split Volume tasks do not work properly when DST is running on the original volume. DFS does not automatically demigrate the data to move or copy it to the move or split destination location.

IMPORTANT:Before you use the Move Volume task or Split Volume task on an NSS volume, you must modify the volume’s DST policies to force it to demigrate data from the secondary volume to the primary volume.

Make sure you have enough space available on the primary volume to demigrate the data. When the demigration is complete, turn off DST shadowing on the volume, and leave it off until the move or split is complete. Now, you can define a Move Volume or Split Volume job on the original volume.

After a Move Volume job is complete, you can optionally configure DST shadowing on the new volume.

After a Split Volume job is complete, you can optionally configure DST shadowing on the original volume. Data that was split to the new location is not affected by shadowing that you set up on the original volume. In order to shadow the data that was moved to a new location, you must set up DST shadowing on that target volume.