Date: Wed, 21 Feb 2007 08:06:07 -0600
From: Robert Hancock <hancockr@shaw.ca>
Subject: Re: libata FUA revisited
In-reply-to: <45DC04DF.8040002@gmail.com>
To: Tejun Heo <htejun@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>,
       linux-kernel <linux-kernel@vger.kernel.org>, linux-ide@vger.kernel.org,
       edmudama@gmail.com, Nicolas.Mailhot@LaPoste.net,
       Jeff Garzik <jeff@garzik.org>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Mark Lord <mlord@pobox.com>, Ric Wheeler <ric@emc.com>,
       Dongjun Shin <d.j.shin@samsung.com>, Hannes Reinecke <hare@suse.de>
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Tejun Heo wrote:
>> Aside from the issue above, as I mentioned elsewhere, lots of NCQ drives
>> don't support non-NCQ FUA writes..
> 
> To me, using the NCQ FUA bit on such drives doesn't seem to be a good
> idea.  Maybe I'm just too chicken but it's not like we can gain a lot
> from doing FUA at this point.  Are there a lot of drives which support
> NCQ but not FUA opcodes?

Well, it's hard to say whether "lots" have this issue, but the ones I 
have in my machine, Seagate 7200.7 NCQ 160GB (ST3160827AS) and 7200.10 
320GB (ST3320620AS), both support NCQ and don't support non-NCQ FUA, and 
those (especially the latter) seem to be very popular models.

Likely Seagate didn't implement that command since they figured nobody 
would use that if they had NCQ..

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/

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