Question about LTO compression

Hi,
 In some cases  I find that an unexpectedly small amount of data is written to LTO tapes, just a little more than it should be able to contain without compression.
Is there a way to check how much data on LTO tapes is compressed in Data Protector ?

  • Hello Agnar

    Compression is done by drive directly DP is not aware about that, compression ratio will depend about number of files types that you are copying.

    You will get more compression for "office" files than for .jog files that are already compressed.

    http://blog.open-e.com/a-few-words-about-hardware-compression-in-a-backup-with-tape-drives/

    Anyway if you want check compression feature please use LTT tools for to run some tests.

    https://www.hpe.com/us/en/product-catalog/storage/storage-software/pip.406729.html

    Best Regards

     

     

  • Hello,

    Looking at your query - Is there a way to check how much data on LTO tapes is compressed in Data Protector ?

    I guess it should be "what are the ways to check how much data on LTO tapes is compressed on a DP backup".

    I may suggest that you log a DP SUPPORT CASE as this may need deep investigation - first would be to check how things are configured - HW OS   APPLICATION (DP side).

    Same as what was mentioned in one of the reply - this depends on a lot of factors.

    I would recommend to check the HW first - LTO Library/drives, and then determine the objects (files) you are backing-up.

     

    Hope this helps

    rgds,

    Sherman

    HPE DP SUPPORT

     

  • Hello,

    The support centre can't check from a distance your infrastructure. You can't expect them to drill down into your SAN zoning f.i. just to make my point.

    LTT is prob ably the simpliest to test/check your compression ratio.

    If you'd like to see it from a DP point of view; simple:

    make a backup of a know amount of data

    what's written on tape

    restore your data (preferably somewhere else)

    compare initial in- and final out-put

    compile now your personal compression formula :-)

    Luc

  • Hello,

    Yes - I am not looking at the whole infrastructure, such as the SAN zoning configuration.

    What I mean by HW is information on the tape library/drives. What I mean by OS is what files is being backed-up.

    And YES, I would concentrate more on the DP side - I need to check what is the device configuration (omnidownload) and the backup specification.

    I need to check things first before recommending any "test backup". And any test backup will be dependent on what cu have.

    Rgds,

    Sherman

    HPE DP Support