Hi Lars,
On Fri, Jul 26, 2002 at 11:57:25AM +0200, Lars Soltau wrote:
> >
> > 2. [...] So one is not supposed to copy a dump from tape onto a disk file
> > and
> > then restore it. [...]
>
> Well, that's not very helpful. :-)
>
> I had some old tapes and borrowed a matching streamer to restore them.
> After the restore directly from tape failed with an assertion failure
> (see blow), I copied the files to disk because I had to return the
> streamer before I had a chance to do a full examination of the assertion
> failure.
>
> I ended up patching drive_minrmt.c to forget about all SCSI commands and
> open consecutively numbered files on hard disk instead.
Ahhh, the beauty of open source :)
> It would be a nice feature for xfsrestore to be able to open a tape
> backup from disk, wouldn't it?
>
I guess ;-)
It would be nice if the dump format was independent of the
dump tape commands - at the moment using a "dump tape" strategy means using
the dump tape format with the tape scsi commands.
> > 3. I don't know why xfsrestore is aborting with an assertion failure for
> > you.
>
> I do, now. I single-stepped into the assertion and found out that one
> 64bit offset in each record header, the first_mark_offset, had been
> written highendian instead of littleendian. All the other offsets, for
> example file_offset that is located directly before first_mark_offset,
> had been written correctly.
>
If you check out the cmd/xfsdump/doc/CHANGES file, it was fixed
in December last year:
xfsdump-1.1.10 (10 December 2001)
- fix xfsdump to endian convert all of the record header
fields properly just prior to writing the header out
(in particular first_mark_offset).
This caused do_next_mark() assertion failures at some
sites.
> The backup has been written by a version of xfsdump compiled with egcs
> on Linux. Personally, I suspect egcs's 64bit arithmetic. Anyway, I
> patched the source to correct the offset on the fly and the problem
> vanished.
Good.
The mail archive:
http://marc.theaimsgroup.com/?l=linux-xfs&m=101435725816823&w=2
had suggestions for restoring from the bad dumps.
Cheers,
--Tim
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