Re: Raid5 device hangs in active state

[Larkin Lowrey <llowrey@nuclearwinter.com>]

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I did another sysrq dump and have attached the output.

Again, 'iostat -dx 1' showed 100% utilization on the LVM which uses
/dev/md0 as a pv and /sys/block/md0/md/stripe_cache_active was 29 and
that value did not change. There were no error messages in
/var/log/messages or 'dmesg'.

My suspicions lie with md0 since the stripe_cache_active value remains
at a fixed non-zero value even though all disks are (or appear to be)
idle. Should I be looking elsewhere? This hardware did not exhibit this
problem before "upgrading" from Fedora 15 to Fedora 16.

Thank you,

--Larkin

On 1/8/2012 6:26 PM, NeilBrown wrote:
> On Sun, 08 Jan 2012 16:03:10 -0600 Larkin Lowrey
<llowrey@nuclearwinter.com>
> wrote:
>
>> Suggestions?
>
> # echo t > /proc/sysrq-trigger
>
> and capture that messages that go to 'dmesg'. Post them.
>
> Hopefully your message ring buffer is big enough to collect the entire
> output. If it isn't you might need to boot with
> log_buf_len=1M
> or similar.
>
> That should show what process is blocking on what.
>
> NeilBrown


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