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  • Veritas Backup compression Issues

    Hello all, hope all is well.

    I have an issue with veritas 9.1 rev 4691 running on a windows 200 server. both are fully up to date, and have preiously been backing up quite happily. however all of a sudden the compression on the tapes has dropped from 2:1 (or there abouts to 0.5:1.

    I have scoured the veritas and HP/IBM sites for why this might have happened (the tape drive is an IBM branded HP LTO tape drive)

    I have done the following and still get the issue:

    reinstalled veritas completely from scratch, and applied all relevent updates and latest veritas drivers
    built a new media set of brand new tapes
    created a fresh backup job from scratch

    has anyone got any ideas?

    cheers

    UB

  • #2
    Re: Veritas Backup compression Issues

    I may be way of base here but I'm wondering if Veritas works like Arcserve.

    If data compression is set on the drive itself (ie Hardware compression) then the compression used by the software won't work (Software compression) I get this problem from time to time if someone reboots a server without consulting me first.

    In Arcserve I have to insert a blank tape and then disable compression on the drive (device) then I can enable it in the software.

    As I say I may be off base here but it may help you
    The Univurse is still winning!

    W2K AD, WSUS, RIS 2003. ISA also AVG Server
    ** If contributors help you, recognise them and give reputation points where appropriate **

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    • #3
      Re: Veritas Backup compression Issues

      Hi Andy, your location is East Yorkshire UK - near Hull at all?
      Server 2000 MCP
      Development: ASP, ASP.Net, PHP, VB, VB.Net, MySQL, MSSQL - Check out my blog http://tonyyeb.blogspot.com

      ** Remember to give credit where credit is due and leave reputation points sigpic where appropriate **

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      • #4
        Re: Veritas Backup compression Issues

        Aye Tony I live in Hull (Anlaby)
        Work in Brigg
        Last edited by AndyUK; 11th September 2006, 12:51.
        The Univurse is still winning!

        W2K AD, WSUS, RIS 2003. ISA also AVG Server
        ** If contributors help you, recognise them and give reputation points where appropriate **

        Comment


        • #5
          Re: Veritas Backup compression Issues

          I work in Hull at Wilberforce College. What company do you work for?
          Server 2000 MCP
          Development: ASP, ASP.Net, PHP, VB, VB.Net, MySQL, MSSQL - Check out my blog http://tonyyeb.blogspot.com

          ** Remember to give credit where credit is due and leave reputation points sigpic where appropriate **

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          • #6
            Re: Veritas Backup compression Issues

            Psst, (move the social stuff to the Lounge guys. Thanks).
            1 1 was a racehorse.
            2 2 was 1 2.
            1 1 1 1 race 1 day,
            2 2 1 1 2

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            • #7
              Re: Veritas Backup compression Issues

              Originally posted by biggles77
              Psst, (move the social stuff to the Lounge guys. Thanks).
              Will do
              Server 2000 MCP
              Development: ASP, ASP.Net, PHP, VB, VB.Net, MySQL, MSSQL - Check out my blog http://tonyyeb.blogspot.com

              ** Remember to give credit where credit is due and leave reputation points sigpic where appropriate **

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              • #8
                Re: Veritas Backup compression Issues

                In Veritas, you need not disable hardware compression for software compression to work. The software tells the tape drive what to do at the beginning of each job.

                I have no idea why the compression would change suddenly, but perhaps you might look at the following.

                Average compression is always estimated at 2 to 1. This is why tapes say "40GB Native, 80GB Compressed." It's just an estimate. The real factor in compression is the file as it is being taken off the hard drive. Word documents typically lose about 50% of their bulk when compressed. Excel spreadsheets often lose a whopping 90%. Other pre-compressed files, like GIFs and ZIP files either lose next to nothing or actually become LARGER in size by the time they get to tape.

                Software compression in Veritas does a better job of compressing. Hardware compression is faster, but not as effective. So if you are trying to compress files that are already pre-compressed, hardware compression will likely make them larger.

                One other thing that might effect the results you see is disk compression. If you already have your files compressed on the data drives, then it is possible that the Veritas software must first decompress the file off the disk, then recompress it to put it on tape. This could screw up the statistics. I know it shouldn't work that way, but it might. Unfortunately, getting a straight answer for this type of question is now near impossible because Veritas shipped their tech support overseas to Bombay, and I have noticed that if the question AND the answer isn't already in the Knowledge Base, you aren't going to get an answer.

                There is a possibility you might get an intelligent answer to this by contacting the tape drive manufacturer. One other thing you might try is to use a different software package as a test to see if you get the same compression results. At least this would help you to sort out the culprit.

                Hope this helps.

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