From: Ric Wheeler <ric@emc.com>
To: Mark Rustad <mrustad@gmail.com>
Cc: Jeff Garzik <jeff@garzik.org>,
Justin Piszcz <jpiszcz@lucidpixels.com>,
linux-kernel@vger.kernel.org,
IDE/ATA development list <linux-ide@vger.kernel.org>
Subject: Re: Why is NCQ enabled by default by libata? (2.6.20)
Date: Sat, 31 Mar 2007 08:55:45 -0400 [thread overview]
Message-ID: <460E5A51.7010601@emc.com> (raw)
In-Reply-To: <711F1620-F483-4CC2-83D6-F2DD577AB5BB@gmail.com>
Mark Rustad wrote:
> On Mar 27, 2007, at 1:38 PM, Jeff Garzik wrote:
>
>> Mark Rustad wrote:
>>> reorder any queued operations. Of course if you really care about
>>> your data, you don't really want to turn write cache on.
>>
>> That's a gross exaggeration. FLUSH CACHE and FUA both ensure data
>> integrity as well.
>>
>> Turning write cache off has always been a performance-killing action
>> on ATA.
>
> Perhaps. Folks I work with would disagree with that, but I am not
> enough of a storage expert to judge. My statement mirrors the
> judgement of folks I work with that know more than I do.
You can easily demonstrate that disabling write cache on a S-ATA or ATA
drive will drop your large file write performance by 50% - just try
writing 10MB files to disk.
ric
next prev parent reply other threads:[~2007-03-31 12:56 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-24 16:38 Why is NCQ enabled by default by libata? (2.6.20) Justin Piszcz
2007-03-24 18:43 ` Alan Cox
2007-03-27 9:55 ` Justin Piszcz
2007-03-27 10:10 ` Tejun Heo
2007-03-27 10:30 ` Justin Piszcz
2007-03-27 5:59 ` Jeff Garzik
2007-03-27 14:26 ` Mark Lord
2007-03-27 18:18 ` Mark Rustad
2007-03-27 18:38 ` Jeff Garzik
2007-03-27 22:12 ` Mark Rustad
2007-03-31 12:55 ` Ric Wheeler [this message]
[not found] <fa.MhN9pBMjZID4rnTNn+fU01uZiss@ifi.uio.no>
2007-03-24 22:11 ` Robert Hancock
-- strict thread matches above, loose matches on Subject: below --
2007-03-27 16:16 linux
2007-03-27 16:25 ` Justin Piszcz
2007-03-27 16:41 ` linux
2007-03-27 16:44 ` Justin Piszcz
2007-03-27 16:58 ` linux
2007-03-27 17:03 ` Justin Piszcz
2007-03-28 14:42 ` Phillip Susi
2007-03-28 14:48 ` Jeff Garzik
2007-03-28 15:22 ` Andy Warner
2007-03-29 17:28 ` Phillip Susi
2007-03-29 18:40 ` linux
2007-03-29 18:51 ` Jeff Garzik
2007-03-29 21:35 ` Alan Cox
2007-03-29 21:47 ` David Schwartz
2007-03-30 16:33 ` Lennart Sorensen
[not found] <fa.NmF2xJwO4BeVbJrFRkf7oV9EYmQ@ifi.uio.no>
[not found] ` <fa.39luedDWsoqip+QMNtfAv8jvyNg@ifi.uio.no>
[not found] ` <fa.b1cZfpMNhZ0teK/UauKLDWw60Jc@ifi.uio.no>
[not found] ` <fa.xWaBy6HZTRTgI+PxinV8ajuOlJI@ifi.uio.no>
[not found] ` <fa.BiSx71HKysC9QIpS8DLip5BmfxI@ifi.uio.no>
2007-04-01 17:28 ` Robert Hancock
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