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From: "Justin Piszcz" <jpiszcz@lucidpixels.com>
To: linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org
Subject: 3.12: raid-1 mismatch_cnt question
Date: Mon, 4 Nov 2013 05:25:28 -0500	[thread overview]
Message-ID: <000f01ced948$2fbab140$8f3013c0$@lucidpixels.com> (raw)

Hi,

I run two SSDs in a RAID-1 configuration and I have a swap partition on a
third SSD.  Over time, the mismatch_cnt between the two devices grows higher
and higher.

Once a week, I run a check and repair against the md devices to help bring
the mismatch_cnt down.  When I run the check and repair, the system is live
so there are various logs/processes writing to disk.  The system also has
ECC memory and there are no errors reported.

The following graph is the mismatch_cnt from June 2013 to current; each drop
represents a check+repair.  In September, I dropped the kernel/vm caches
before running check/repair and that seemed to help a bit.
http://home.comcast.net/~jpiszcz/20131104/md_raid_mismatch_cnt.png

My question is: is this normal or should the mismatch_cnt always be 0 unless
there is a HW or md/driver issue?

Justin.


WARNING: multiple messages have this Message-ID (diff)
From: "Justin Piszcz" <jpiszcz@lucidpixels.com>
To: <linux-kernel@vger.kernel.org>, <linux-raid@vger.kernel.org>
Subject: 3.12: raid-1 mismatch_cnt question
Date: Mon, 4 Nov 2013 05:25:28 -0500	[thread overview]
Message-ID: <000f01ced948$2fbab140$8f3013c0$@lucidpixels.com> (raw)

Hi,

I run two SSDs in a RAID-1 configuration and I have a swap partition on a
third SSD.  Over time, the mismatch_cnt between the two devices grows higher
and higher.

Once a week, I run a check and repair against the md devices to help bring
the mismatch_cnt down.  When I run the check and repair, the system is live
so there are various logs/processes writing to disk.  The system also has
ECC memory and there are no errors reported.

The following graph is the mismatch_cnt from June 2013 to current; each drop
represents a check+repair.  In September, I dropped the kernel/vm caches
before running check/repair and that seemed to help a bit.
http://home.comcast.net/~jpiszcz/20131104/md_raid_mismatch_cnt.png

My question is: is this normal or should the mismatch_cnt always be 0 unless
there is a HW or md/driver issue?

Justin.


             reply	other threads:[~2013-11-04 10:25 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-04 10:25 Justin Piszcz [this message]
2013-11-04 10:25 ` 3.12: raid-1 mismatch_cnt question Justin Piszcz
2013-11-07 10:54 ` Justin Piszcz
2013-11-12  0:39   ` Brad Campbell
2013-11-12  9:14     ` Justin Piszcz
     [not found] ` <527E8B74.70301@shiftmail.org>
2013-11-09 22:49   ` Justin Piszcz
2013-11-10 12:45     ` joystick
2013-11-11  9:26       ` Justin Piszcz
2013-11-11 11:06         ` joystick
2013-11-11 18:52           ` Justin Piszcz
2013-11-11 21:23             ` John Stoffel
2013-11-11 21:55               ` NeilBrown
2013-11-12  2:49                 ` John Stoffel
2013-11-11 21:58             ` NeilBrown
2013-11-11 22:18               ` Justin Piszcz
2013-11-12  9:30             ` joystick
2013-11-12 10:29               ` Bernd Schubert
2013-11-13 22:10                 ` Justin Piszcz
2013-11-14  8:44                   ` joystick
2013-11-14 10:43                     ` Justin Piszcz
2013-11-14 16:09                       ` joystick
2013-11-14 17:22                         ` Justin Piszcz
2013-11-15  8:51                           ` joystick

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