Date: Wed, 9 Sep 2009 13:02:18 +0100
From: Chris Webb <chris@arachsys.com>
To: linux-scsi@vger.kernel.org
Cc: Tejun Heo <tj@kernel.org>, Ric Wheeler <rwheeler@redhat.com>,
       Andrei Tanas <andrei@tanas.ca>, NeilBrown <neilb@suse.de>,
       linux-kernel@vger.kernel.org,
       IDE/ATA development list <linux-ide@vger.kernel.org>,
       Jeff Garzik <jgarzik@redhat.com>, Mark Lord <mlord@pobox.com>
Subject: Re: MD/RAID time out writing superblock
Message-ID: <20090909120218.GB21829@arachsys.com>
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Chris Webb <chris@arachsys.com> writes:

> I've also noticed that during this recovery, I'm seeing lots of timeouts but
> they don't seem to interrupt the resync:
> 
>   05:47:39 ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
>   05:47:39 ata5.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 0 pio 512 in
>   05:47:39         res 40/00:00:00:4f:c2/00:00:00:00:00/40 Emask 0x4 (timeout)
>   05:47:39 ata5.00: status: { DRDY }
>   05:47:39 ata5: hard resetting link
>   05:47:49 ata5: softreset failed (device not ready)
>   05:47:49 ata5: hard resetting link
>   05:47:49 ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
>   05:47:49 ata5.00: configured for UDMA/133
>   05:47:49 ata5: EH complete
>   
>   08:17:39 ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
>   08:17:39 ata5.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 0 pio 512 in
>   08:17:39         res 40/00:00:35:83:f8/00:00:4d:00:00/40 Emask 0x4 (timeout)
>   08:17:39 ata5.00: status: { DRDY }
>   08:17:39 ata5: hard resetting link
>   08:17:49 ata5: softreset failed (device not ready)
>   08:17:49 ata5: hard resetting link
>   08:17:49 ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
>   08:17:49 ata5.00: configured for UDMA/133
>   08:17:49 ata5: EH complete
>   
>   10:22:39 ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
>   10:22:39 ata5.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 0 pio 512 in
>   10:22:39         res 40/00:00:00:4f:c2/00:00:00:00:00/40 Emask 0x4 (timeout)
>   10:22:39 ata5.00: status: { DRDY }
>   10:22:39 ata5: hard resetting link
>   10:22:49 ata5: softreset failed (device not ready)
>   10:22:49 ata5: hard resetting link
>   10:22:50 ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
>   10:22:51 ata5.00: configured for UDMA/133
>   10:22:51 ata5: EH complete

... the difference being that a timeout which causes a super_written failure
seems to return an I/O error whereas the others don't:

  ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
  ata5.00: cmd ea/00:00:00:00:00/00:00:00:00:00/a0 tag 0
          res 40/00:00:00:00:00/00:00:00:00:00/a0 Emask 0x4 (timeout)
  ata5.00: status: { DRDY }
  ata5: hard resetting link
  ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
  ata5.00: configured for UDMA/133
  ata5: EH complete
  end_request: I/O error, dev sde, sector 1465147272
  md: super_written gets error=-5, uptodate=0
  raid10: Disk failure on sde3, disabling device.

I wonder what's different about these two timeouts such that one causes an I/O
error and the other just causes a retry after reset? Presumably if the latter
was also just a retry, everything would be (closer to being) fine.

Cheers,

Chris.
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