Re: Tape read/write problems - TechNote 010-100586 - Veritas Backup Exec

This is a discussion on Re: Tape read/write problems - TechNote 010-100586 - Veritas Backup Exec ; In article , Ken McNulty es.co.uk> writes >I am seeing a lot of mail with about tape read/write problems which seem to >be in the same area. I would refer people to Veritas TechNote 010-100586, >which may be of interest. ...

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Thread: Re: Tape read/write problems - TechNote 010-100586

  1. Re: Tape read/write problems - TechNote 010-100586

    In article <3847b013@hronntp01.?>, Ken McNulty es.co.uk> writes
    >I am seeing a lot of mail with about tape read/write problems which seem to
    >be in the same area. I would refer people to Veritas TechNote 010-100586,
    >which may be of interest. We are having a problem doing restores, even
    >though the saves seemed to work OK. I would suggest that everyone attempts
    >to do a restore to see what happens. If there's a problem, you want to find
    >out about it now, not when you're in deep .... and your boss is saying,
    >"Well, haven't you tested this ?". Go on, have a go. Pick a file down a
    >couple of directories, deep in the tape.


    It's always a good idea to do this sort of "random restore" test
    periodically, also every time you change a tape drive, drive firmware,
    NT Service Pack, controller card drivers or BENT version.


    In the meanwhile, do you care to list the items in the problematic
    setup?






    David
    --
    David Wood david@wood2.demon.co.uk
    Please post any replies to this group - "post and mail" is not needed.
    DISCLAIMER: I am not an employee of Veritas, merely a user who's trying
    to share his ideas and experience. Follow my advice at your own risk.

  2. Re: Tape read/write problems - TechNote 010-100586

    We were getting "An inconsistency was encountered on the storage media in
    [our tape 20/40GB DLTdrive]", when we tried to restore a single file from
    deep down in the tape. However when we tried to restore a single file near
    the top of the tape, it worked OK. By that I mean that the file we were
    trying to restore was numerically (according to Explorer) far from the first
    file in the first folder on the disk. I worked my way back up Explorer's
    list, trying different folders and different levels of subfolder until I
    managed to restore a file that was directly under the first folder on the
    disk.

    I then tried using a tape which had been used for full disk restores a
    couple of days earlier. The savesets that had been used were the second and
    third on the tape. Still I couldn't restore a deep file from the same
    saveset that hade been successfully restored in its entirety a few days
    earlier, on the same drive. I tried restoring to another system using
    another drive without success. I tried restoring other systems tapes to the
    failing system, and they worked.

    I eventually narrowed things down to two systems for which I could do full
    disk restores, but not individual deep files. I consulted Veritas' Technical
    Support Forum and found a number of entries with the ".... incosistency
    encountered ..." message. The reply to one of them (03/26/99) was, " Your
    system is having trouble finding file access markers through our fast seek
    mechanisms, disabling the keys should allow you to find your data. Disable
    these registry keys:
    HKey_Local_Machine\Software\SeagateSoftware\Backup Exec\Engine\TapeFormat\Use
    Fast File Append and Use Fast File Restore = "0x1" is the default, change to
    just "0"".

    I did just that, except I substituted Veritas for SeagateSoftware because we
    are on 7.3. It worked, except it took five hours to find the file. In other
    words, disabling the Fast Find keys means the software runs down the tape at
    the same speed as it would when running a full disk restore. It also
    explains why the full restores worked, they don't use Fast Find keys,
    although it found the savesets quickly.
    But why the problem? One of the Forum entries directed me to TechNote
    010-100586, the last entry of which is, "Isolate the tape drive on its own
    controller".

    One other entry said that they'd tried new tapes, new device, upgrade
    software etc. They were getting errors on verifying and had come to the
    conclusion that the problem lay with auto-termination on any device on the
    SCSI channel. I quote, "Playing around with various configurations of
    termination I found that the slightest mis-configuration of the SCSI
    channels would cause this failure, sometimes intermittently. In the end we
    have reduced our configuration to using Auto Term on the Adaptec card and
    nothing else." A bit like the TechNote's, "Isolate the tape drive ?".
    Interestingly enough, we suspect problems on the Disk Arrays on the two
    systems we have restore problems with. We are awaiting down-time to let the
    engineers check and re-seat (their suggestion) the SCSI boards.

    I appreciate this is a bit long-winded, but so's the problem. If you check
    the TechNote, you will see that talks about all kinds of SCSI
    checks/parameters. I think that there are general problems in this area
    associated with SCSI cards, possibly high-performance tape
    drives and Fast Find markers.

    Ken McNulty


    David Wood wrote in message ...
    >In article <3847b013@hronntp01.?>, Ken McNulty >es.co.uk> writes
    >>I am seeing a lot of mail with about tape read/write problems which seem

    to
    >>be in the same area. I would refer people to Veritas TechNote 010-100586,
    >>which may be of interest. We are having a problem doing restores, even
    >>though the saves seemed to work OK. I would suggest that everyone attempts
    >>to do a restore to see what happens. If there's a problem, you want to

    find
    >>out about it now, not when you're in deep .... and your boss is saying,
    >>"Well, haven't you tested this ?". Go on, have a go. Pick a file down a
    >>couple of directories, deep in the tape.

    >
    >It's always a good idea to do this sort of "random restore" test
    >periodically, also every time you change a tape drive, drive firmware,
    >NT Service Pack, controller card drivers or BENT version.
    >
    >
    >In the meanwhile, do you care to list the items in the problematic
    >setup?
    >
    >
    >
    >
    >
    >
    >David
    >--
    >David Wood david@wood2.demon.co.uk
    >Please post any replies to this group - "post and mail" is not needed.
    >DISCLAIMER: I am not an employee of Veritas, merely a user who's trying
    >to share his ideas and experience. Follow my advice at your own risk.




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