Best ways to increase efficiency of aux copies

Last post 05-15-2019, 3:34 AM by Wwong. 3 replies.
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  • Best ways to increase efficiency of aux copies
    Posted: 05-10-2019, 1:36 PM

    Are there things that increase efficiency for aux copies, such as:

    • Using the same deduplication factor on both primary and aux; or
    • Using the same encryption method on both primary and aux?
    Is there a way to have a primary and an aux in the same storage policy share a dedupe database, or not explode the data before re-deduplicating, re-compressing, re-encrypting?
  • Re: Best ways to increase efficiency of aux copies
    Posted: 05-13-2019, 8:21 AM

    Hi Sheree

    When you refer to Aux Copy, is this:

    • Aux Copy from Local to Cloud - if this is the case Local should be using 128 KB Block Size for DDB, and Cloud DDB should be using 512 KB.
    • Aux Copy from Local Disk to Disk - both DDB should be using 128 KB 
      • Depending on the type of Storage Array (i.e Isilon, NetApp, Synology, HDS and etc) there will be specific recommendation
    • Aux Copy from Local Disk to Tape - this will depend on the Read from Source Storage, Network and the Physical Write to Tape (no Deduped involved)
    If you are currently using Encryption, you can consider using the option "Preserve Encryption from Source" which will mitigate from the need of re-encrypting the data when writing to Secondary. 
    Commvault will not allow you to share the same DDB for two copy in the same Storage Policy, as that is a single Point of Failure (and even if Commvault allows you to do so, you will never configure it that way). 
    If you have Deduplication on Source and Destination, you can enable DASH Copy, which is only comparing the unique signature on Source and transfering/incrementing the Seocndary DDB (which will greatly improve overall throughput/completion time as there are less data to transfer over the wire). 
    There are various factors to consider, but if you can share your specific scenario, we can assist or provide more recommendation inline to Commvault Best Practice. 
  • Re: Best ways to increase efficiency of aux copies
    Posted: 05-14-2019, 3:00 PM

    Hi Winston,

    Doesn't using a different Deduplication Factor on Primary vs. Aux copies make DASH copies not work?  It seems like hashes of 128KB and 512KB wouldn't be comparable.

    Our scenario is 'Setting up brand-new media agents with local storage and a new aux copy to AWS'.  They've been set up as aux copy targets from the old media agents, and once they have enough retention, this aux copy will be promoted to Primary and we'll switch to using these media agents and a new DDB for the AWS copy, since we want to switch the AWS copy from a 128KB to 512KB deduplication factor.




  • Re: Best ways to increase efficiency of aux copies
    Posted: 05-15-2019, 3:34 AM

    Hi Sheree

    For best Read/Write performance to Cloud DDB, we recommend to use 512 KB

    Documentation -

    Originally we didn't support having different DDB with different Block Size in the same Storage Policy, but in later versions that has been ammended. 





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