trying to read backup tape from 1992 - SCO

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  1. trying to read backup tape from 1992

    I have a client that abandoned SCO UNIX in 1992 and has
    asked me to retrieve data from old backup tapes.

    I have a set of 10 tapes, only one of which I have
    successfully restored to a directory on my system.

    The problem is that the tapes are DC600A 60M tapes
    and the cpio backup spans two tapes. After restoring
    the one tape i can read, the restore asks for the
    second tape. But all the second tapes fail to read
    with the message I/O error 5.

    One of the second tapes reads to 3M, most read from 160k
    to 1M before the error occurs.

    I've tried dd if=/dev/rct0 of=tape.raw bs=512 but
    dd has the same problem as cpio: It gets to a point on the tape
    and then indicates that it can't read the media.
    I've tried bs=5120 and bs=1k, bs=10k bs=20 without success.

    Is there any way to place a SCSI tape into raw mode to
    have it ignore errors and just extract what it can to
    a file?

    I've tried the nrct0 device and when the error occurs, tried
    tape wfm to try to skip the bad section of the tape and
    then use the cpio -k option to read beyond the error without
    success.

    The "tape eod" command positions the tape to the end of data
    but I have not been able to cause the tape to rewind to the
    point of the I/O error.

    I know that I will loose the file that was written spanning the tape,
    but there are other files beyond that I need to retrieve.

    The likely cause of the problem was that no one was concerned
    when the system was shut down to run a run a cleaning cartridge
    through the tape drive and write a final backup. Had I been
    involved at the time, I would have adjusted the backup to write
    the data directory to a separate tape so that the data would
    fit on one tape.

    I've got to check with the client to see if anyone thought to
    pull the hard drive and place it in storage. Failing that,
    I will have to try other means to position the tape beyond the
    area throwing the I/O error and get what data I can from the
    tape.
    --

    Steve Fabac
    S.M. Fabac & Associates
    816/765-1670

  2. Re: trying to read backup tape from 1992

    Steve M. Fabac, Jr. wrote:
    > I have a client that abandoned SCO UNIX in 1992 and has
    > asked me to retrieve data from old backup tapes.
    >
    > I have a set of 10 tapes, only one of which I have
    > successfully restored to a directory on my system.
    >
    > The problem is that the tapes are DC600A 60M tapes
    > and the cpio backup spans two tapes. After restoring
    > the one tape i can read, the restore asks for the
    > second tape. But all the second tapes fail to read
    > with the message I/O error 5.
    >
    > One of the second tapes reads to 3M, most read from 160k
    > to 1M before the error occurs.
    >
    > I've tried dd if=/dev/rct0 of=tape.raw bs=512 but
    > dd has the same problem as cpio: It gets to a point on the tape
    > and then indicates that it can't read the media.
    > I've tried bs=5120 and bs=1k, bs=10k bs=20 without success.
    >
    > Is there any way to place a SCSI tape into raw mode to
    > have it ignore errors and just extract what it can to
    > a file?


    Not sure if this would be of any help to you Steve but linux has a great
    version of dd called dd_rescue. It is a dd that will continue on even
    if it encounters io errors. I even use it to get data off of failing
    windows disks. It might be worth a look as it could create a dd image
    of your tapes with 00s filled in for the unreadable parts. If you don't
    have a linux system with the proper tape drive you could try the knoppix
    live cd. It contains the dd_rescue utlity.

    Good Luck

    Glenn

    >
    > I've tried the nrct0 device and when the error occurs, tried
    > tape wfm to try to skip the bad section of the tape and
    > then use the cpio -k option to read beyond the error without
    > success.
    >
    > The "tape eod" command positions the tape to the end of data
    > but I have not been able to cause the tape to rewind to the
    > point of the I/O error.
    >
    > I know that I will loose the file that was written spanning the tape,
    > but there are other files beyond that I need to retrieve.
    >
    > The likely cause of the problem was that no one was concerned
    > when the system was shut down to run a run a cleaning cartridge
    > through the tape drive and write a final backup. Had I been
    > involved at the time, I would have adjusted the backup to write
    > the data directory to a separate tape so that the data would
    > fit on one tape.
    >
    > I've got to check with the client to see if anyone thought to
    > pull the hard drive and place it in storage. Failing that,
    > I will have to try other means to position the tape beyond the
    > area throwing the I/O error and get what data I can from the
    > tape.
    > --
    >
    > Steve Fabac
    > S.M. Fabac & Associates
    > 816/765-1670


  3. Re: trying to read backup tape from 1992

    On 2007-04-15, Steve M. Fabac, Jr. wrote:
    > I have a client that abandoned SCO UNIX in 1992 and has
    > asked me to retrieve data from old backup tapes.


    Have you already warned the client about the probability of success?
    Even with the best media and ideal storage, 15 years is pushing it
    a bit.

    > I've tried dd if=/dev/rct0 of=tape.raw bs=512 but
    > dd has the same problem as cpio: It gets to a point on the tape
    > and then indicates that it can't read the media.
    > I've tried bs=5120 and bs=1k, bs=10k bs=20 without success.
    >
    > Is there any way to place a SCSI tape into raw mode to
    > have it ignore errors and just extract what it can to
    > a file?


    Have you tried adding conv=noerror (or possibly conv=noerror,sync)
    to your dd parameters? You will lose some data but it shouldn't
    be a showstopper for the data after the bad patch on the tape.

    --
    Andrew Smallshaw
    andrews@sdf.lonestar.org

  4. Re: trying to read backup tape from 1992

    On Apr 15, 1:40 pm, "Steve M. Fabac, Jr." wrote:
    > I have a client that abandoned SCO UNIX in 1992 and has
    > asked me to retrieve data from old backup tapes.
    >
    > I have a set of 10 tapes, only one of which I have
    > successfully restored to a directory on my system.
    >
    > The problem is that the tapes are DC600A 60M tapes
    > and the cpio backup spans two tapes. After restoring
    > the one tape i can read, the restore asks for the
    > second tape. But all the second tapes fail to read
    > with the message I/O error 5.
    >
    > One of the second tapes reads to 3M, most read from 160k
    > to 1M before the error occurs.
    >
    > I've tried dd if=/dev/rct0 of=tape.raw bs=512 but
    > dd has the same problem as cpio: It gets to a point on the tape
    > and then indicates that it can't read the media.
    > I've tried bs=5120 and bs=1k, bs=10k bs=20 without success.
    >
    > Is there any way to place a SCSI tape into raw mode to
    > have it ignore errors and just extract what it can to
    > a file?
    >
    > I've tried the nrct0 device and when the error occurs, tried
    > tape wfm to try to skip the bad section of the tape and
    > then use the cpio -k option to read beyond the error without
    > success.
    >
    > The "tape eod" command positions the tape to the end of data
    > but I have not been able to cause the tape to rewind to the
    > point of the I/O error.
    >
    > I know that I will loose the file that was written spanning the tape,
    > but there are other files beyond that I need to retrieve.
    >
    > The likely cause of the problem was that no one was concerned
    > when the system was shut down to run a run a cleaning cartridge
    > through the tape drive and write a final backup. Had I been
    > involved at the time, I would have adjusted the backup to write
    > the data directory to a separate tape so that the data would
    > fit on one tape.
    >
    > I've got to check with the client to see if anyone thought to
    > pull the hard drive and place it in storage. Failing that,
    > I will have to try other means to position the tape beyond the
    > area throwing the I/O error and get what data I can from the
    > tape.
    > --
    >
    > Steve Fabac
    > S.M. Fabac & Associates
    > 816/765-1670


    What kind/size of tape drive you are using to read these tapes, may be
    you need to use the old Archive 60 MB tape drive to get better result.
    Just a thought

    Abid


  5. Re: trying to read backup tape from 1992

    In article ,
    Andrew Smallshaw wrote:
    >On 2007-04-15, Steve M. Fabac, Jr. wrote:
    >> I have a client that abandoned SCO UNIX in 1992 and has
    >> asked me to retrieve data from old backup tapes.


    >Have you already warned the client about the probability of success?
    >Even with the best media and ideal storage, 15 years is pushing it
    >a bit.


    And if they didn't verify any of the tapes who knows if anything is
    there.

    Years ago I was called into an SCO site I had not seen, and they
    wanted some mods as their SW company 'went away'.

    So before I touched a thing I made a backup on the 1/4" tape.
    Then I tried to read it back.

    NOTHING.

    I took about a dozen swabs to get the gunk off the head.

    I guesstimated it had been over 6 months since they had made
    a readable backup. Of course they rotated the tapes daily so they
    had no backups at all.

    Bill

    --
    Bill Vermillion - bv @ wjv . com

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