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Message-ID: <4AB2610F.8010904@rtr.ca>
Date: Thu, 17 Sep 2009 12:17:19 -0400
From: Mark Lord <liml@....ca>
To: Chris Webb <chris@...chsys.com>
Cc: Tejun Heo <teheo@...e.de>, linux-scsi@...r.kernel.org,
Ric Wheeler <rwheeler@...hat.com>,
Andrei Tanas <andrei@...as.ca>, NeilBrown <neilb@...e.de>,
linux-kernel@...r.kernel.org,
IDE/ATA development list <linux-ide@...r.kernel.org>,
Jeff Garzik <jgarzik@...hat.com>, Mark Lord <mlord@...ox.com>
Subject: Re: MD/RAID time out writing superblock
Mark Lord wrote:
> Tejun Heo wrote:
>> Hello,
>>
>> Mark Lord wrote:
>>> Tejun.. do we do a FLUSH CACHE before issuing a non-NCQ command ?
>>
>> Nope.
>>
>>> If not, then I think we may need to add code to do it.
>>
>> Hmm... can you explain a bit more? That seems rather extreme to me.
> ..
>
> You may recall that I first raised this issue about a year ago,
> when my own RAID0 array (MythTV box) started showing errors very
> similar to what Chris is reporting.
>
> These were easily triggered by running hddtemp once every few seconds
> to log drive temperatures during Myth recording sessions.
>
> hddtemp uses SMART commands.
>
> The actual errors in the logs were command timeouts,
> but at this point I no longer remember which opcode was
> actually timing out. Disabling the onboard write cache
> immediately "cured" the problem, at the expense of MUCH
> slower I/O times.
..
Speaking of which..
Chris: I wonder if the errors will also vanish in your situation
by disabling the onboard write-caches in the drives ?
Eg. hdparm -W0 /dev/sd?
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