Re: mount prob: "log inconsistent or not a log"

["Jonathan C. Detert" <Jonathan.Detert@msoe.edu>]

* Timothy Shimmin <tes@sgi.com> [071219 22:43]:
> Jonathan C. Detert wrote:
> >* Timothy Shimmin <tes@sgi.com> [071219 18:53]:
> >>Hi Jonathan,

-- snip --

> >-- snip --
> >
> >>An "xfs_logprint -d /dev/sdb" will show what the cycle#s are
> >>and where the log records are. It might give an idea of the
> >>extent of the corruption.
> >
> >Ok.  It doesn't enlighten me, but hopefully you or others can take time
> >to see it, and maybe it will enlighten you.  Here it is:
> >-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> >root@quartz:~ # xfs_logprint -d /dev/sdb > xfs_logprint.out
> >xfs_logprint:
> >    data device: 0x810
> >    log device: 0x810 daddr: 39859232 length: 38920
> >
> >[00000 - 00000] Cycle 0xffffffff New Cycle 0x00000256
> >    12 HEADER Cycle 598 tail 598:000010 len    224 ops 5

-- snip --

> > 38770 HEADER Cycle 597 tail 597:036946 len  32256 ops 101
> > 38834 HEADER Cycle 597 tail 597:036946 len  32256 ops 145
> >[25405 - 38888] Cycle 0x00000255 New Cycle 0x00000000
> >root@quartz:~ #
> >-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> 
> Well, that confirms why it won't replay.
> There shouldn't be a cycle# change from 597 to zero.
> This actually shows the cycle#s at the log record headers
> (not all the sector cycle#s).
> 
> At the end we are writing out full iclog buffers of 32k each.
> Hence the length of 32256 and 64 BBs (32k) between the headers.
> 
> Now at the end, we would expect...
> 38834 .. 38834+64=38898 of cycle#s of 597 for that log record.
> But at 38889 it goes to zero cycle#.
> So that log record is corrupted at around 54 BBs (27K into the 32K).
> 
> And then for the last (38920-38888 = 32) BBs (16K) of the
> log we don't find a log record header.
> 
> I would expect the log head to be at the cycle# change from 598->597.
> 
> >  25398 HEADER Cycle 598 tail 598:025428 len    996 ops 14
> >  25401 HEADER Cycle 598 tail 598:025430 len    224 ops 5
> >  25403 HEADER Cycle 598 tail 598:025433 len    224 ops 5 <--- head
> > [00000 - 25405] Cycle 0x00000256 New Cycle 0x00000255
> >  25420 HEADER Cycle 597 tail 597:025329 len  32256 ops 133
> >  25484 HEADER Cycle 597 tail 597:025329 len  32256 ops 112
> >  25548 HEADER Cycle 597 tail 597:025329 len  32256 ops 101
> 
> ie. the last LR written at 598:25403.
> I was surprised to see the tail at the time at 598:25433,
> as that makes the tail into the future.
> That looks weird to me. Or perhaps I'm missing something.

I appreciate your analysis.  I'm barely able to track with you, though,
so I can't say as to whether you're missing anything.

> If there's corruption that was not between the tail to the head,
> then it could be a goer I guess but one would wonder about corruption

what do you mean by 'goer' - hardware failure?

> beyond the end of the log too. But the tail looks weird.
> 
> OOI, can you save the log, compress it and send it to me.

yes; will send it off-list, as it's still 2 MB after compression.
-- 
Jon Detert
IT Systems Administrator, Milwaukee School of Engineering
1025 N. Broadway, Milwaukee, Wisconsin 53202, U.S.A.
--
Never do anything against conscience, even if the state demands it.