Some questions.

Do you get any messages on the screen when it crashes and/or is there
anything in /var/log/messages from the crashes?

Is a sync running when it crashes?   If so what kind of SATA
controllers/setup are you using?  I have had 2 previous setups that
would run fairly stably so long as a sync was not running, but if a
sync was running then the machine became unstable.

Did you umount it and run a "fsck -f -y" that took a while (at least
30 seconds) or just umount it and ran fsck and it finished quickly and
indicated clean?    Generally if you nicely umount it the fs thinks it
is clean even when it is not because of some previous event.

On Fri, Jul 4, 2014 at 8:08 PM, Justin Stephenson
[off-list ref] wrote:

Hi,

Thanks for your reply.

I should clarify that the crashes continue to be an issue in the absence of
any power outage so this issue is now independent of power. I mentioned the
UPS only with the thought that my problems may have been caused by a sudden
power-down.

Please let me know if there are any logs or status print outs I could pull
to help troubleshoot this.

Thanks Again,

- J




------ Original Message ------
From: "Stan Hoeppner" <redacted>
To: "Justin Stephenson" <redacted>;
linux-raid@vger.kernel.org
Sent: 04/07/2014 3:34:17 PM
Subject: Re: RAID 6 crashes system when being accessed

quoted

On 7/4/2014 9:11 AM, Justin Stephenson wrote:

quoted

 Hello,

 I am experiencing some issues with my md raid. It is crashing my system
 when accessed with any "verve". The reboot initiates a resync of the
 raid. I have gone through the crash/reboot/resynced a number of times
 now and the crash happens within minutes of mounting the raid.

 Here are some details:

 - It is a raid 6 with 7 3TB devices.
 - Formatted as EXT4
 - mdadm v3.2.6 - 25th October 2012
 - centos 6.5 kernel 2.6.32-431.3.1.el6.x86_64
 - It has been running flawlessly for the previous 6 months.
 - I have a cron script running that resyncs monthly.
 - When the raid is unmounted, the system runs fine. (I have an
 additional "dumb" hardware raid 1 for dailies attached to an ESATA port.
 This runs perfectly).
 - I am in the process of re-syncing the raid 6 again right now.
 - I have run an fsck on the raid volume after it was fully synced and
 everything came up clean.

 - there have been lots of power outages the last while with the hot
 summer in Toronto. My UPS shuts the system down for me, though I think I
 can correlate the issues with the power outages.

This sounds like the UPS is cutting power to the system before the
shutdown sequence completes, before the array is stopped. This assumes
you are already using apcupsd or similar. If you are check the
configuration to make sure the system has plenty of time to shutdown
after the UPS sends notification to the system. If you are not, then
this will always happen as the UPS is simply cutting power when the
battery gets low.

Note that if the UPS is undersized for this system and only yields a few
minutes of on-battery time, it may simply not have enough juice to keep
the machine up throughout the shutdown process.

In summary, either your shutdown software isn't configured properly, you
are not using it, or the UPS is too small. This isn't an md problem.


Cheers,

Stan

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