Hello Roger,

Thank-you for your email and for laying out some trouble shooting steps 
for me. I will take these to heart and keep them on file for the future.

I can report that there was a screen of rapid scrolling text during the 
crashes and some kind of memory contents dump that had a progress 
indicator. From what I could see, there was some kind of kernel panic 
and a message about ATA-9. Nothing in the /var/log/messages file as far 
as I could see.

I had tried unmounting and running fsck before but not with your 
specified -f -y flags.

Here are the steps I took based on your input.

- ran system overnight with md raid unmounted.
- fully completed resync
- performed fsck -f -y. It took approx 6 minutes (on a 12TB volume). No 
errors reported in the printout.
- reboot
- locally initiated and completed a 22 gb copy from and to the md raid 
and a local esata external drive.

---

- from a workstation, opened SMB share to the MD raid
- workstation initiated copy to and from the CentOS box (and MD drive) 
of the same 22gb folder over SMB.
- opened vnc client to the centOS box from a workstation.

Up until the fsck -f -y any of these three operations would cause a 
crash.


In summary, it would seem that the issue has been resolved by the fsck 
-f -y. Up until running fsck - f -y, the system was completely 
unpredictable when the MD drive was mounted - either during a sync or 
after it was completed. I find this surprising, but perhaps I should 
not?

Based on Stan's email, I checked my UPS power settings, and I am certain 
I was ending up with a hard powerdown when the battery ran out. I have 
remedied this.

Could this have caused the MD volume to become unstable?

In any event, everything is up and running. I will report back with a 
log entry if anything else appears.

Thanks again,

- Justin



------ Original Message ------
From: "Roger Heflin" <redacted>
To: "Justin Stephenson" <redacted>
Cc: stan@hardwarefreak.com; "Linux RAID" <redacted>
Sent: 05/07/2014 12:17:45 AM
Subject: Re: Re[2]: RAID 6 crashes system when being accessed

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:

quoted

 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" [off-list ref]
 To: "Justin Stephenson" [off-list ref];
 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

 --
 To unsubscribe from this list: send the line "unsubscribe linux-raid" 
in
 the body of a message to majordomo@vger.kernel.org
 More majordomo info at http://vger.kernel.org/majordomo-info.html