Date: Mon, 22 Jul 2013 09:02:57 +1000
From: NeilBrown <neilb@suse.de>
To: "Justin Piszcz" <jpiszcz@lucidpixels.com>
Cc: <linux-kernel@vger.kernel.org>, <linux-raid@vger.kernel.org>
Subject: Re: 3.10.1: echo repair > sync_action causes hang on RAID-1 (2 x
 SSD)
Message-ID: <20130722090257.2faa0874@notabene.brown>
In-Reply-To: <000501ce85fc$d3a60a10$7af21e30$@lucidpixels.com>
References: <000501ce85fc$d3a60a10$7af21e30$@lucidpixels.com>
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On Sun, 21 Jul 2013 06:26:55 -0400 "Justin Piszcz" <jpiszcz@lucidpixels.com>
wrote:

> Hi,
>=20
> When I run repair on an MD-RAID1 sync_action, the speed slows down and it
> stays like this (below) for hours. =20
>=20
> The system is then completely unresponsive to user input.  I have replace=
d a
> failing SSD; however, after a check, mismatch_cnt seems to increase over
> time.  When I run repair, the system freezes to user-input.  Has anyone e=
lse
> run into this issue with a RAID-1 volume (2 x SSD) using 0.90 metadata?
> Long ago I used to use this same configuration with two physical disks and
> there was never a problem.
>=20
> Even though I left a root shell open, this has no effect to break the
> resync:
> # echo idle > /sys/devices/virtual/block/md1/md/sync_action
>=20
> Every 1.0s: cat /proc/mdstat                            Sun Jul 21 06:15:=
38
> 2013
>=20
> Personalities : [raid1]
> md1 : active raid1 sdc2[0] sdb2[1]
>       233381376 blocks [2/2] [UU]
>       [>....................]  resync =3D  0.0% (151616/233381376)
> finish=3D36171.5min speed=3D107K/sec
>=20
> md0 : active raid1 sdc1[0] sdb1[1]
>       1048512 blocks [2/2] [UU]
>=20
> unused devices: <none>
>=20
> 10 minutes later:
>=20
>       233381376 blocks [2/2] [UU]
>       [>....................]  resync =3D  0.0% (151616/233381376)
> finish=3D52219.3min speed=3D74K/sec
>=20
> Where it hangs (151616) or elsewhere, has been different each time I watc=
hed
> it, it does not appear to be hanging at the same block each time.
>=20

Hi Justin,
 this is a known bug.  Fix has been accepted into mainline for 3.11-rc2.
 Hopefully it will get into 3.10.3 (too late for 3.10.2).

NeilBrown

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