Auxillary Copy to Tape Performance

Last post 02-01-2019, 3:26 PM by farmer. 5 replies.
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  • Auxillary Copy to Tape Performance
    Posted: 01-31-2019, 9:02 AM

    When performing an auxillary to tape where the original data is DeDuplicated what disk takes the biggest hit? The DDB or the Index cache? I know all of the data has to be re-hydrated during the process. We do not use SILO. We are not getting very good throughput on these jobs considering we have 8GB fiber channel tape drives connected to the Media Agents. A while back we moved our Index cache from internal SSD's to SAN connected SSD's. We were told that the SAN connected SSD's would be every bit as fast as the internal drives but I am starting to think otherwise.

  • Re: Auxillary Copy to Tape Performance
    Posted: 01-31-2019, 9:47 AM

    I would check your Read Speeds from the Source Disk Library. 

    I would test your Tape Drive Throughput out to to make sure your Writes are as fast you would expect. 

    The DDB would not really come into play for your Tape copy.

    Yes SAN attched Index Cache is not reccommened and could be the bottle neck ( since it is easy to move) can you move it back to local SSD to see if this majes an improvement? If it does not then check the other items I noted. 


  • Re: Auxillary Copy to Tape Performance
    Posted: 01-31-2019, 11:07 AM

    What tape drive technology are you using.

    We are using LTO7.  Just for comparison, in the commvault GUI running a 'validate drive' with default setting of 2 x 2GB chunks, I get a write speed of 146 MB/sec, and read of 157 MB/sec.

  • Re: Auxillary Copy to Tape Performance
    Posted: 01-31-2019, 1:32 PM

    The tape validation was run on a new media agent that was not put into production yet.  I just updated the Windows drivers from the MS driver to the IBM LTO7 driver and now the speed is 240 MB/sec write and 256 MB/sec read.

    I am curiuos to what speed you are seeing for what hardware.


  • Re: Auxillary Copy to Tape Performance
    Posted: 01-31-2019, 1:43 PM

    We have a IBM 3590 library with E07 3592 Tape Drives. When I validate I get a throughput of 204MB/sec writes and 512MB/sec reads.

  • Re: Auxillary Copy to Tape Performance
    Posted: 02-01-2019, 3:26 PM

    simialr to thread

    changing the block size in the data path config from default to 512k, it spead up quite a bit.

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