Re: access beyond end of device errors in 2.2.13pre18 AND 2.2.5

Martin Schulz (schulz@iwrmm.math.uni-karlsruhe.de)
29 Oct 1999 16:24:11 +0200


"Stephen C. Tweedie" <sct@redhat.com> writes:

> 1.2.2-4?? That is ancient, and there was a bug in knfsd's rmdir
> operation which could cause exactly these symptoms. Please upgrade to
> knfsd-1.4.7 and see if you can reprodce the problem.

Well I did this yesterday night an upgraded to knfsd-1.4.7-7 and
kernel 2.2.13 as Alan Cox suggested. But there again the very first
backup run yielded:

Oct 29 01:59:37 iwr01 kernel: attempt to access beyond end of device
Oct 29 01:59:37 iwr01 kernel: 08:11: rw=0, want=2045247456, limit=8924076
Oct 29 01:59:37 iwr01 kernel: dev 08:11 blksize=1024 blocknr=-102236193 sector=-204472386 size=1024 count=1
Oct 29 01:59:37 iwr01 kernel: attempt to access beyond end of device
Oct 29 01:59:37 iwr01 kernel: 08:11: rw=0, want=1879039744, limit=8924076
Oct 29 01:59:37 iwr01 kernel: dev 08:11 blksize=1024 blocknr=-268443905 sector=-536887810 size=1024 count=1

(Btw, what do the negative values mean, or it is just an integer overflow?)

> We know that (a) dodgy hardware

I don't think that my problem is in hardware. I suspected my hardware
for quite a while. Other boxes with nearly identical hardware run rock
solid for some months now.

> and (b) the knfsd problem can explain
> huge numbers of these reports,

Well. I through out knsfd and installed the nfs-server-2.2beta40-1
package and at *very* first glance things seem to be better now. At
least the first two backup runs were fine. I keep my fingers crossed,
though, since the above errors occurred only from time to time.

> but it's hard to completely exclude the
> possibility of other faults in the current kernels. It would really
> help to eliminate variables if you could go to a more recent knfsd.

Well, I did that. That box is not my playground, but the central
server of our (small, but working) group that I cannot shutdown at
will.

For this machine, stable operation is of much more importance
than the last 20% performance, so I won't tweek it if not really
necessary.

I tried to reproduce the effects on a (client) machine without nfs
server and tar'ed both to /dev/null and to real tape, but a handfull
of runs could not reproduce it. Dammned thing.

Would it help to have two playground boxes set aside? Is there such a
thing like a nfs-client-simulator? I reaaly do not want to abuse my
nonvirtual users for that purpose.

regards,

-- 
Martin Schulz                             schulz@iwrmm.math.uni-karlsruhe.de
Uni Karlsruhe, Institut f. wissenschaftliches Rechnen u. math. Modellbildung
Engesser Str. 6, 76128 Karlsruhe

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