Bug#510641: mdadm: checkarray emits messages for auto-read-only md devices

[Philipp Kern]

Package: mdadm
Version: 2.6.7.1-1

I just got alerted by mdadm with this:
/usr/share/mdadm/checkarray: line 167: echo: write error: Device or resource busy

Actually it tried to write to /sys/block/md0/md/sync_action and it seems that
md0 does not like that.  It works fine with md1 and md2.  The mdstat is as
follows:

Personalities : [raid0] [raid1]
md2 : active raid1 sda3[0] sdb3[1]
      486014336 blocks [2/2] [UU]

md1 : active raid1 sda2[0] sdb2[1]
      264960 blocks [2/2] [UU]

md0 : active (auto-read-only) raid1 sda1[0] sdb1[1]
      2104448 blocks [2/2] [UU]

The md devices were created by a setup script and md0 holds the swap space
which is, I think, the rationale for using auto-read-only.  I'm not
exactly sure about its semantic, i.e. if a resync is skipped completely
and the device could be newly written but mirrored for this session
or if it's just kept read-only until the first swap occurs and thus
not dirty if nothing happens.  At least this is what array_state tells
me:

# cat /sys/block/md0/md/array_state
read-auto
# cat /sys/block/md1/md/array_state
clean

Kind regards,
Philipp Kern
-- 
 .''`.  Philipp Kern                        Debian Developer
: :' :  http://philkern.de                         Release Assistant
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