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Volume size on FCM3 Standard Pools

  • 1.  Volume size on FCM3 Standard Pools

    Posted 3 days ago


     I'm migrating some volumes from older controllers (2076-624 with RTC compression and 2076-724 with DRP) to a brand new 7300 with FCM3-only drives and I'm a little puzzled about the volume size/used figures on the new FCM system.

      My issue is like this :

    • on 7300 I've created a standard pool , I want to get rid of all the DRP stuff and use only the drive compression
    • the 7300 volumes are thin
    • I've replicated a few volumes from the older systems to the new system with GMCV or GM
    • on the older systems the volumes were around 50% used.  The volume size is strictly corelated with the used mdisk space after compression for that volume
    • after replication I'm surprised to see that the auxiliary volumes are 100% full on the 7300 system. Both the master and the aux have the same volume size of course and they are in sync. However, the used volume size is 50% on the older system and 100% on the new system.
    • on the FCM system the drive compression is working fine at the pool level. I have a compression ratio greater than 2:1 so the actual usable storage is as expected but I'm puzzled about the volume size/usage concepts on the 7300 system considering that I'm already getting thin provisioned volume copy space warnings :)
    • my guess is that on the FCM pool the volume size and the volume usage is actually considerred based on the max written data and not on the actually used mdisk space as on the older system. Is this correct or am I doing something wrong ?



    Adrian Nicolae