[linux-lvm] Powerfailure and snapshot consistency

[Stuart D. Gathman]

On Mon, 28 Mar 2011, Phillip Susi wrote:

> On 3/27/2011 5:55 PM, Stuart D. Gathman wrote:
>> Don't need help, just trying to understand the event.  So from what you
>> said, the problem probably stems from the RAID1 resync, which could
>> make one PV "older" than the other.
>
> The data is written to the primary mirror first, so this can't happen.
> Proper use of barriers will prevent this whole scenario, so my guess is
> that you are using ext3 ( which defaults to nobarrier ) or explicitly
> mounting ext4 with nobarrier.

Ah, thank you!  Yes, I am using ext3 with EL5.5 defaults, and will now learn
about the barrier option.  Seems like a good thing to turn on when "replace
battery" comes up on the ups.

It sounds like dumb luck/divine mercy that the raid 1 PV on which the
production LV resides did not have a similar issue.

--
 	      Stuart D. Gathman <stuart at bmsi.com>
     Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
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