AMS/HUS Volume migration

Sometime, due to a number of different reasons, there might be a need to perform an undisruptive LUN migration from one DP pool to another. Thankfully it’s trivially easy to do with AMS/HUS Hitachi’s storage arrays:

  1. First, enable Volume Migration if this option is still off:
  2. auopt -unit array_name -option VOL-MIGRATION -st enable
    
  3. Create a new LUN that will be used as a destination:
  4. auluadd -unit array_name -lu 2 -dppoolno 1 -size 1468006400 -widestriping enable -fullcapacity enable
    
  5. Create a special LUN called DMLU (Differential Management Logical Unit) which will be keeping the differential data during migration. Please not that this LUN can’t be less than 10GB and full capacity mode could not be enabled for it:
  6. auluadd -unit array_name -lu 3 -dppoolno 1 -size 70G -widestriping enable
    audmlu -unit array_name -set -lu 3
    
  7. Start LUN migration from source (LUN 1) to destination LUN (LUN 2) that we’ve created recently:
  8. aumvolmigration -unit array -add -lu 2
    aumvolmigration -unit array -create -pvol 1 -svol 2
    
  9. Basically, we’ve just paired two LUNs together and started the copy from one to another. To see the progress run the following command:
  10. aumvolmigration -unit array_name -refer
    
  11. Once the copy is over, the pair could be split and since the LUN’s id where the data live doesn’t change, the destination LUN, in our example that was LUN 2, could be deallocated and freed:
  12. aumvolmigration -unit array_name -split -pvol 1 -svol 2
    

Just a reminder, to make the migration non disruptive the original LUN id must not change, and that’s why in the end the only LUN id that could be deleted is that we created during step 2 – LUN with id 2.

That’s it. Have fun and safe migrations.