Aggregated pre-compression size of data for all tapes in a Storage Policy Copy?

Last post 03-22-2019, 9:17 PM by Wwong. 5 replies.
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  • Aggregated pre-compression size of data for all tapes in a Storage Policy Copy?
    Posted: 03-21-2019, 10:00 PM

    We have a bunch of non-deduped, hardware-compressed data on tape that we need to copy to disk.  We need to know how much disk we'll need.  Is there a way to find the actual space consumed by the data, or (better) the amount of data transferred to the tapes before the tape drive compressed it?

    (We're not restoring it; it will still be Commvault data. We just want to move it.)

    ... Is the 'Data in Storage Policy Copy' view showing me this?  The numbers in this view vs. the 'Disk Space Utilization' Library view are way off for the deduped stuff, but maybe it's more accurate for non-deduped stuff?

  • Re: Aggregated pre-compression size of data for all tapes in a Storage Policy Copy?
    Posted: 03-22-2019, 1:15 AM

    Hi Sheree 

    So if you are going to Aux Copy Tape back to Disk (without Deduplication or Compression), then the Backup will consume the exact size of the "Application Size" column. 

    However if you are going to use compression, then it becomes a bit tricky as different data set will have different compression ratio, so will not be possible to calculate. 

    I recommend to Aux Copy one job (with Compression) and then check the size on disk after the Aux Copy to compare the percentage saving and use that as a general benchmark to calculate the require capacity for disk

    Regards

    Winston 

  • Re: Aggregated pre-compression size of data for all tapes in a Storage Policy Copy?
    Posted: 03-22-2019, 2:25 PM

    Hi Wwong,

    This is data that was already proven to be un-dedupable before we put it on tape, so we won't be trying to dedupe it.  Thanks for the tip about the Application Size.

  • Re: Aggregated pre-compression size of data for all tapes in a Storage Policy Copy?
    Posted: 03-22-2019, 7:33 PM

    Hi Sheree

    No issue test out the Aux Copy back from the Tape to Disk and see how it goes.

    Regards

    Winston 

  • Re: Aggregated pre-compression size of data for all tapes in a Storage Policy Copy?
    Posted: 03-22-2019, 7:53 PM

    Hi Winston,

    I appreciate your help, but this is probably hundreds of terabytes of data, and we don't have that sort of storage lying around to "see how it goes." We really need to know before we allocate the storage, since it's such a large amount.  So I hope you're right about that Application Size metric. LOL.

  • Re: Aggregated pre-compression size of data for all tapes in a Storage Policy Copy?
    Posted: 03-22-2019, 9:17 PM

    Hi Sheree

    As mentioned before in one of my updates: 

    "I recommend to Aux Copy one job (with Compression) and then check the size on disk after the Aux Copy to compare the percentage saving and use that as a general benchmark to calculate the require capacity for disk"

    The above test will give you an indication on how much potential space will be consumed, so you can then work whether this will be feasible for the business. 

    Kind Regards

    Winston

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