From: Mikael Abrahamsson <swmike@swm.pp.se>
To: Jon Nelson <jnelson-linux-raid@jamponi.net>
Cc: Phil Turmel <philip@turmel.org>,
Florian Lampel <florian.lampel@gmail.com>,
LinuxRaid <linux-raid@vger.kernel.org>
Subject: Re: RAID6 dead on the water after Controller failure
Date: Sun, 16 Feb 2014 00:04:13 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.02.1402160001340.14422@uplift.swm.pp.se> (raw)
In-Reply-To: <CAKuK5J0jxUUvkAY-U2Q6v5j9hf_nasOQOjvFGe+ThYaDFRt7yA@mail.gmail.com>
On Sat, 15 Feb 2014, Jon Nelson wrote:
> Out of 12 drives, I thought RAID6 only offered a total of *2* failed
> devices. It seems to me that you have 7 devices in sync and 4 *almost*
> in sync. It's this "almost" part that has me confused. How can the raid
> run if the event count doesn't match? Wouldn't at least 10 out of 12
> drives have to have the same event count to avoid data loss?
Correct. When you use --assemble --force you're basically telling mdadm "I
know what I'm doing and I'll take the risk of data loss or corruption". If
you assemble in with a kicked drive that was kicked long ago that has a
really far off event count, you can really really screw things up.
Unless you use --force, mdadm won't assemble an array where the event
count doesn't match up.
--
Mikael Abrahamsson email: swmike@swm.pp.se
next prev parent reply other threads:[~2014-02-15 23:04 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-14 16:19 RAID6 dead on the water after Controller failure Florian Lampel
2014-02-14 20:35 ` Phil Turmel
2014-02-15 12:31 ` Florian Lampel
2014-02-15 15:12 ` Phil Turmel
2014-02-15 18:52 ` Florian Lampel
2014-02-15 19:00 ` Phil Turmel
2014-02-15 19:01 ` Phil Turmel
2014-02-15 19:09 ` Bakk. Florian Lampel
2014-02-15 22:04 ` Jon Nelson
2014-02-15 23:04 ` Mikael Abrahamsson [this message]
2014-02-15 23:23 ` Jon Nelson
2014-02-16 3:49 ` Phil Turmel
[not found] ` <CADNH=7EiY18TJDBDQsT6LDtw+Ft_2XCFaP30uK7uJb_e7xKhsQ@mail.gmail.com>
2014-02-15 18:56 ` Florian Lampel
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