| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 3762.1 | Oh, oh! | JULIET::ROYER | Greening up our lives. | Wed May 21 1997 18:13 | 15 |
| Did you do a verify pass after writing the backup tape?
No verify, then the backup probably did not write properly. If verify
done, then try the cleaning tape and then retry the restore. DAT
media/hardware is very problematical at best, I would never use one for
data that I thought I might like to restore some day.
I say this from the perspective of being a MVCS Engineer, they are the
worse backup device (DAT) in the world. Basically what you have is a
Video Cassette Recorder, that is modified to put digital data on a
media instead of a picture. Bit dropout on a video usually results in
a flicker, some lines or a missed frame. The same result on data can
be really severe.
Dave
|
| 3762.2 | Now that you mention it... | MARVIN::GOUGH | Raoul Gough | Thu May 22 1997 12:58 | 26 |
|
> Did you do a verify pass after writing the backup tape?
No I didn't, but I'm starting to think that I should have. Cleaning the heads
didn't help, so I guess that .1 is right, the tape was written with the
error.
> ...
> DAT media/hardware is very problematical at best, I would never use one
> for data that I thought I might like to restore some day.
> ...
> Dave
I can afford to be flippant about it now, because I managed to get most of
the data off the tape by fooling around for a few hours with dd and mt. I
read the first part of the dump, up to near the error, and then skipped a bit
and then got the remainder of the dump from after the error. If I ever tried
to actually read data from the error region, the tape required re-loading.
So then I got the two halves and glued them together before using "restore",
which complained about missing files, but restored all the other ones.
Not a problem.
Thanks for your reply,
Ray.
|
| 3762.3 | | LEFTY::CWILLIAMS | CD or not CD, that's the question | Thu May 22 1997 18:24 | 5 |
| re: .1 --- You've obviously never tried the old 8mm drives, or you
would have a higher opinion of DAT. The old 8mm was the closest thing
to a write-only media I've ever seen.
Chris
|
| 3762.4 | | WARFUT::MELLING | | Fri May 23 1997 01:32 | 16 |
|
Hello,
Did you happen to look in the errorlog to see if an error was
recorded there.
I had a problem of not being able to VRESTORE data from a tape
which had previously given no indication of a problem during the
VDUMP.
I would be most interested in either the decevent output or the
uerf -Z output from your errorlog.
Perhaps you could enter it here or mail it to me on warhed::melling
regards
tony
|
| 3762.5 | Records no longer available, but... | MARVIN::GOUGH | Raoul Gough | Tue May 27 1997 18:35 | 34 |
| Re: .4
After restoring the dump (as outlined in .2) my uerf record was overwritten,
since it resides on the partition which I restored.
However, at the time of the original problem I started to produce a record
of what was happening, and here's an extract:
My restore command was "restore -rYf /dev/nrmt0h"...
Tape read error while restoring ./share/man/man3/wcscat.3.gz
continue? [yn] y
cam_logger: CAM_ERROR packet
cam_logger: bus 4 target 4 lun 0
ctape_iodone
Hard Error Detected
DEC TLZ07 (C)DECTLZ07
Active CCB at time of error
CCB request completed with an error
Error, exception, or abnormal condition
HARDWARE ERROR - Nonrecoverable hardware error
I don't have DecEvents, but maybe the above will help you. The tape was
written with Data compression (the default with dump) and I wonder if it
would have recovered from the error better without the compression.
Regards,
Ray.
> I would be most interested in either the decevent output or the
> uerf -Z output from your errorlog.
|