Data Compression Rates - Veritas Backup Exec

This is a discussion on Data Compression Rates - Veritas Backup Exec ; I am using an HP SureStore DAT24 External Tape Drive with Backup Exec v. 7.3 build 2575. The HP Drive is supposed to back up 24 gigs compressed, however, we are only able to do approx 17 gigs before the ...

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Thread: Data Compression Rates

  1. Data Compression Rates


    I am using an HP SureStore DAT24 External Tape Drive with Backup Exec v. 7.3
    build 2575. The HP Drive is supposed to back up 24 gigs compressed, however,
    we are only able to do approx 17 gigs before the tape runs out of space.

    We are using the max data compression available, and are backing up mostly
    mailboxes through exchange 5.5, word/excel docs, tif's, gif's, access databases
    etc. Anyone have an idea why the tape runs out of space much sooner than
    it should?


    Thanks,
    Vik


  2. Re: Data Compression Rates

    Vik,

    In my (probably limited) experience, the compressed
    estimates (and they are just that, estimates) are generally
    low, and are extremely dependent on the type of file being
    backed up. However, have you tried changing the compression
    type from hardware to software (or software to hardware)? I
    have had luck in certain situations with that.

    Regards,
    Todd,

    "Vik" wrote in message
    news:3d5920e0$1@hronntp01....
    >
    > I am using an HP SureStore DAT24 External Tape Drive with

    Backup Exec v. 7.3
    > build 2575. The HP Drive is supposed to back up 24 gigs

    compressed, however,
    > we are only able to do approx 17 gigs before the tape runs

    out of space.
    >
    > We are using the max data compression available, and are

    backing up mostly
    > mailboxes through exchange 5.5, word/excel docs, tif's,

    gif's, access databases
    > etc. Anyone have an idea why the tape runs out of space

    much sooner than
    > it should?
    >
    >
    > Thanks,
    > Vik
    >




  3. Re: Data Compression Rates

    "Vik" wrote in message news:3d5920e0$1@hronntp01....
    >
    > We are using the max data compression available, and are backing up mostly
    > mailboxes through exchange 5.5, word/excel docs, tif's, gif's, access

    databases
    > etc. Anyone have an idea why the tape runs out of space much sooner than
    > it should?
    >


    TIFF, GIF are pretty much compressed already, and so is exchange db (I
    think). You won't get much compression ratio out of those files. If you're
    backing up text files (like us), the tape will probably handle more than
    17GB. 24GB is just an approximate rate based on 2:1 compression ratio. You
    will or will not be able to get 24GB depending on the data set.

    >
    > Thanks,
    > Vik
    >




  4. Re: Data Compression Rates


    "Todd Denlinger" wrote:
    >Vik,
    >
    >In my (probably limited) experience, the compressed
    >estimates (and they are just that, estimates) are generally
    >low, and are extremely dependent on the type of file being
    >backed up. However, have you tried changing the compression
    >type from hardware to software (or software to hardware)? I
    >have had luck in certain situations with that.
    >
    >Regards,
    >Todd,
    >
    >"Vik" wrote in message
    >news:3d5920e0$1@hronntp01....
    >>
    >> I am using an HP SureStore DAT24 External Tape Drive with

    >Backup Exec v. 7.3
    >> build 2575. The HP Drive is supposed to back up 24 gigs

    >compressed, however,
    >> we are only able to do approx 17 gigs before the tape runs

    >out of space.
    >>
    >> We are using the max data compression available, and are

    >backing up mostly
    >> mailboxes through exchange 5.5, word/excel docs, tif's,

    >gif's, access databases
    >> etc. Anyone have an idea why the tape runs out of space

    >much sooner than
    >> it should?
    >>
    >>
    >> Thanks,
    >> Vik
    >>

    >
    >





    Hi!

    You can imagine that the data-compression works like winzip - some files
    can be compressed up to 80%, others canīt be compressed (e.g. jpeg-files).
    so the fillgrade of the tape depends on the the files you save.



  5. Re: Data Compression Rates

    As already lined out ... the 24GB is just an estimate based on the
    assumption you could achive a 2:1 compression ratio. Usually you will get a
    1,5:1 ratio (based on mixed content of text-files, graphics, archives,
    databases ...), so that would be 18GB ... the 24GB is just something every
    vendor puts on it's label but I really doubt in real life you will achive
    such a compression ratio (except your backing only text-files and stuff).

    "Vik" schrieb im Newsbeitrag news:3d5920e0$1@hronntp01....
    >
    > I am using an HP SureStore DAT24 External Tape Drive with Backup Exec v.

    7.3
    > build 2575. The HP Drive is supposed to back up 24 gigs compressed,

    however,
    > we are only able to do approx 17 gigs before the tape runs out of space.
    >
    > We are using the max data compression available, and are backing up mostly
    > mailboxes through exchange 5.5, word/excel docs, tif's, gif's, access

    databases
    > etc. Anyone have an idea why the tape runs out of space much sooner than
    > it should?





  6. Re: Data Compression Rates

    "Henning Eiben" wrote in message
    news:3d5b78a3$1@hronntp01....
    > As already lined out ... the 24GB is just an estimate based on the
    > assumption you could achive a 2:1 compression ratio. Usually you will get

    a
    > 1,5:1 ratio (based on mixed content of text-files, graphics, archives,
    > databases ...), so that would be 18GB ... the 24GB is just something every
    > vendor puts on it's label but I really doubt in real life you will

    achive
    > such a compression ratio (except your backing only text-files and stuff).
    >


    At one time, my backup went past 24GB (believe it or not). I'm backing up
    mostly small text (TXT) files. The tape took as much as 25GB and the backup
    was completed successfully. I guess I got greater than 2:1 compression
    ratio.



  7. Re: Data Compression Rates

    > was completed successfully. I guess I got greater than 2:1 compression
    > ratio.


    Yes, that does happen sometimes. We have a client with a large Oracle
    database. This database gets compressed at about 8:1 according to Backup
    Exec (using software compression).

    -Rod



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