ADSM-L

[no subject]

2015-10-04 17:51:04

Thanks for the info.  I figure I would go with the 2:1 rate when ordering tapes.  It is better to have too many then not enough.  Thanks again.

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    From:   Andy Raibeck[SMTP:storman AT US.IBM DOT COM]
    Reply To:       ADSM: Dist Stor Manager
    Sent:   Wednesday, November 18, 1998 12:46 PM
    To:     ADSM-L AT VM.MARIST DOT EDU
    Subject:        Re: Client Compression Rate

    Hello Linda,

    It is almost impossible for me to tell you what the ADSM compression
    ratios would be for your data. This is because compression ratios
    vary, depending on the type of data being compressed. For instance,
    text files compress very nicely while files that are already
    compressed will not compress very well; in fact, they may even grow!

    Even your 3575 won't realize 3:1 compression on data that is already
    compressed. A very popular question goes something like, "IBM says
    I should be getting 30 GB on a 10 GB tape with 3590 compression, but
    my tapes are getting full and they have only 9 - 11 GB of data on
    them. What am I doing wrong?" The answer to this is that they are
    probably backing up a lot of data that is already compressed (like
    .ZIP files) or they are using client compression.

    ADSM uses an industry standard compression algorithm so if I had to
    give a number, I'd say 2:1 to 3:1, depending on the type of data
    you are backing up. Again, though, your mileage may vary!   :-)

    I would recommend backing up one or two systems that are
    representative of your clients and see what kind of compression
    ratios they yield. Then you can try to extrapolate from there.

    Sorry I can't be more accurate.

    Regards,

    Andy

    Andy Raibeck
    IBM Storage Systems Division
    ADSM Client Development
    e-mail: storman AT us.ibm DOT com
    "The only dumb question is the one that goes unasked."

    This is probably directed more to IBM but I would appreciated it if any one
    has any info or can point me in the right direction.  (I feel like I am
    going around in circle)

    I still have questions concerning the Client Compression Rate.

    Server: AIX 4.2.1 with ADSM 3.1.5
    Clients:  NT ver 2.x.x
              NT ver 3.x.x
    Tape Library: 3575-L24

    I have client compress on due to network issues.  I need to est. the amount
    of tapes needed for roughly 600 PCs.   My question is what kind of compress
    rate can I expect using Client Compress.  (I am aware of the compression
    ratio for the 3575 - raw 3:1).  I placed a service call but so far all they
    have told me is the capacity of the library.  HELP! If I get an answer back
    from IBM, I will post it.  Thank in Advanced.

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