Re: Dump/restore mystery (off topic)
From: Triffid (triffid_at_nebula.net)
Date: 12/03/04
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Date: Thu, 02 Dec 2004 22:48:04 -0500
Triffid wrote:
> Not a Solaris question, actually CX/SX - but the relevant newsgroups
> have been dormant for 10+ years so I'll try my luck here. I think I need
> a lateral thought, but none have come to me yet...
>
> I am responsible for some ancient Harris systems running CX/SX. Some
> background here:
>
> http://tinyurl.com/5e3s4
>
> One of them refused to reboot after an unscheduled power outage last
> weekend - hard disk failure. This should not have been a problem - it
> happens with monotonous regularity - I just drop in a new disk, boot
> from tape, and restore the latest backup.
>
> This time it didn't work. The restore script reported numerous instances
> of "file not found on tape". The system was (barely) bootable after
> restore, but many files and directories were missing. I tried several
> backup tapes with the same result, leading me to conclude the tape drive
> had been writing unreadable backups for some time without reporting any
> errors.
>
> I tried restoring a backup from another system with identical hardware
> and similar software configuration as I figured I could reconcile the
> differences without too much difficulty. This worked, but I cannot
> backup and restore the resulting system - I get the same "file not found
> on tape" errors.
>
> I've narrowed the issue down somewhat:
>
> 1. Backup tape from System B restores without error on System A
> 2. System A boots normally after restore, and appears to be a perfect
> System B clone
> 3. Backup of System A immediately after restore completes without error
> 4. Attempt to restore System A from step 3 tape gives numerous "file not
> found on tape" errors
> 5. Swap out the System A tape drive (6 times so far!) and repeat from
> step 1 - same result!
>
> So it seems to me I either have 6 tape drives that boot and read just
> fine, but can't write a usable backup tape - or something else is
> causing the problem. 6 tape drives with the same problem seems highly
> unlikely. The backup script must be identical (since it was restored
> from System B), as must the restore script (it's on the boot partition
> of the backup tape), so WTF is going on here?
>
> TIA
>
> Triffid
Found the problem :-)
Most (but not all) of the symbolic links on System B have modification
timestamps of May 5th, 2038. I'm not sure how or when this happened, but
a dump tape from July, 2003 has normal mtimes so it was not a Y2K
rollover issue.
When System B is dumped and restored, the incorrect symbolic link mtimes
change to December 1, 1904. When these are dumped, restore can't find them.
I could kick myself for spending so much time on this problem before
noticing the bad mtimes, but that's how hindsight works...
Triffid
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