* "attempt to access beyond end of device" when reshaping raid10 from near=2 to offset=2
@ 2021-01-27 22:15 Daniel Gnoutcheff
2021-01-28 0:59 ` antlists
0 siblings, 1 reply; 3+ messages in thread
From: Daniel Gnoutcheff @ 2021-01-27 22:15 UTC (permalink / raw)
To: linux-raid
Greets,
Whilst experimenting with array reshaping, I've found that if I create a
near=2 raid10 like so:
for i in 0 1 2 3 ; do
truncate --size=1G disk$i
losetup /dev/loop$i disk$i
done
mdadm --create /dev/md0 --level=raid10 --raid-devices=4 --layout=n2 \
--data-offset=10M /dev/loop{0,1,2,3}
mdadm --wait /dev/md0 # wait for resync
and then try to reshape it to offset=2:
mdadm --grow /dev/md0 --layout=o2
the reshape repeatedly fails and restarts with something like this in
dmesg (repetitive messages snipped):
> Jan 27 15:47:07 snaptest kernel: md: reshape of RAID array md0
> Jan 27 15:47:07 snaptest kernel: md: minimum _guaranteed_ speed: 1000 KB/sec/disk.
> Jan 27 15:47:07 snaptest kernel: md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for reshape.
> Jan 27 15:47:07 snaptest kernel: md: using 128k window, over a total of 2076672k.
> Jan 27 15:47:08 snaptest kernel: attempt to access beyond end of device
> Jan 27 15:47:08 snaptest kernel: loop2: rw=536870912, want=2097280, limit=2097152
> Jan 27 15:47:08 snaptest kernel: md/raid10:md0: Disk failure on loop2, disabling device.
> md/raid10:md0: Operation continuing on 3 devices.
> Jan 27 15:47:08 snaptest kernel: attempt to access beyond end of device
> Jan 27 15:47:08 snaptest kernel: loop0: rw=536870912, want=2097280, limit=2097152
> Jan 27 15:47:08 snaptest kernel: md/raid10:md0: Disk failure on loop0, disabling device.
> md/raid10:md0: Operation continuing on 2 devices.
> Jan 27 15:47:08 snaptest kernel: attempt to access beyond end of device
> Jan 27 15:47:08 snaptest kernel: loop1: rw=536870912, want=2097280, limit=2097152
> Jan 27 15:47:08 snaptest kernel: attempt to access beyond end of device
> Jan 27 15:47:08 snaptest kernel: loop1: rw=536870912, want=2097408, limit=2097152
> Jan 27 15:47:08 snaptest kernel: attempt to access beyond end of device
> Jan 27 15:47:08 snaptest kernel: loop1: rw=536870912, want=2097536, limit=2097152
> Jan 27 15:47:08 snaptest kernel: attempt to access beyond end of device
> Jan 27 15:47:08 snaptest kernel: loop1: rw=536870912, want=2097664, limit=2097152
<snip>
> Jan 27 15:47:09 snaptest kernel: loop3: rw=536870912, want=2097408, limit=2097152
> Jan 27 15:47:09 snaptest kernel: attempt to access beyond end of device
> Jan 27 15:47:09 snaptest kernel: loop3: rw=536870912, want=2097536, limit=2097152
> Jan 27 15:47:09 snaptest kernel: attempt to access beyond end of device
> Jan 27 15:47:09 snaptest kernel: loop3: rw=536870912, want=2097664, limit=2097152
<snip>
> Jan 27 15:47:09 snaptest kernel: loop3: rw=536870912, want=2106368, limit=2097152
> Jan 27 15:47:09 snaptest kernel: md: md0: reshape interrupted.
> Jan 27 15:47:09 snaptest kernel: md: reshape of RAID array md0
> Jan 27 15:47:09 snaptest kernel: md: minimum _guaranteed_ speed: 1000 KB/sec/disk.
> Jan 27 15:47:09 snaptest kernel: md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for reshape.
> Jan 27 15:47:09 snaptest kernel: md: using 128k window, over a total of 2076672k.
> Jan 27 15:47:09 snaptest kernel: attempt to access beyond end of device
> Jan 27 15:47:09 snaptest kernel: loop1: rw=536870912, want=2107520, limit=2097152
<snip>
and so on until the array is stopped.
This log came from a Debian stretch VM (mdadm v3.4 and kernel 4.9.246 as
patched and built by Debian), but I see the same behavior in Debian
buster (mdadm v4.1) with stock and backport kernels (4.19.160 and
5.9.15, respectively).
I notice that if I stop, re-assemble, and add back the "failed" devices,
eg.:
mdadm --assemble /dev/md0 /dev/loop{0,1,2,3}
mdadm /dev/md0 --add /dev/loop0
mdadm /dev/md0 --add /dev/loop2
then it recovers and reshapes without complaint.
Have I encountered a bug?
Many thanks,
--
Daniel Gnoutcheff
Systems Administrator
Software Freedom Law Center
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: "attempt to access beyond end of device" when reshaping raid10 from near=2 to offset=2
2021-01-27 22:15 "attempt to access beyond end of device" when reshaping raid10 from near=2 to offset=2 Daniel Gnoutcheff
@ 2021-01-28 0:59 ` antlists
2021-01-28 21:50 ` Daniel Gnoutcheff
0 siblings, 1 reply; 3+ messages in thread
From: antlists @ 2021-01-28 0:59 UTC (permalink / raw)
To: Daniel Gnoutcheff, linux-raid
On 27/01/2021 22:15, Daniel Gnoutcheff wrote:
> Greets,
>
> Whilst experimenting with array reshaping, I've found that if I create a
> near=2 raid10 like so:
I seem to remember this coming up very recently. And I also seem to
remember them coming up with fixes but I'm not sure if it's solved.
So if you search the archive you should find a recent thread and an
update should fix it properly soon.
Oh - and as for Stretch, old mdadm and Ubuntu are known to be, shall we
say, problematic when you reshape an array, so please try not to ... :-)
Cheers,
Wol
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: "attempt to access beyond end of device" when reshaping raid10 from near=2 to offset=2
2021-01-28 0:59 ` antlists
@ 2021-01-28 21:50 ` Daniel Gnoutcheff
0 siblings, 0 replies; 3+ messages in thread
From: Daniel Gnoutcheff @ 2021-01-28 21:50 UTC (permalink / raw)
To: antlists, linux-raid
On 1/27/21 7:59 PM, antlists wrote:
> I seem to remember this coming up very recently. And I also seem to
> remember them coming up with fixes but I'm not sure if it's solved.
>
> So if you search the archive you should find a recent thread and an
> update should fix it properly soon.
>
> Oh - and as for Stretch, old mdadm and Ubuntu are known to be, shall we
> say, problematic when you reshape an array, so please try not to ... :-)
Thanks for warning me about reshapes on stretch. I was in fact planning
some reshapes on a production stretch system. I shall reconsider. :)
I would be curious to read the thread in which the raid10 layout reshape
issue has already been discussed, but I've not been able to find it. I
tried 'raid10 reshape', 'raid10 layout reshape', 'raid layout reshape',
and 'reshape "attempt to access beyond end of device"' in the search box
at [1], and I've skimmed the subject lines for the last two month's
worth of messages, but I couldn't find anything applicable. Are there
other terms I should try?
[1] https://www.spinics.net/lists/raid/
Many thanks,
--
Daniel Gnoutcheff
Systems Administrator
Software Freedom Law Center
^ permalink raw reply [flat|nested] 3+ messages in thread
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