From: James Bottomley <James.Bottomley@SteelEye.com>
To: "Dieter Nützel" <Dieter.Nuetzel@hamburg.de>
Cc: James Bottomley <James.Bottomley@SteelEye.com>,
Chris Mason <mason@suse.com>,
Linux Kernel List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] 2.4.x write barriers (updated for ext3)
Date: Fri, 01 Mar 2002 10:00:09 -0600 [thread overview]
Message-ID: <200203011600.g21G09V01987@localhost.localdomain> (raw)
In-Reply-To: Message from Dieter =?iso-8859-15?q?N=FCtzel?= <Dieter.Nuetzel@hamburg.de> of "Fri, 01 Mar 2002 16:26:27 +0100." <200203011626.27719.Dieter.Nuetzel@hamburg.de>
Dieter.Nuetzel@hamburg.de said:
> How do you checked it?
I used sginfo from Doug Gilbert's sg utilities (http://www.torque.net/sg)
The version was sg3_utils-0.98
Dieter.Nuetzel@hamburg.de said:
> But when I use "scsi-config" I get under "Cache Control Page": Read
> cache enabled: Yes Write cache enabled: No
I believe write cache enabled is the state of the WCE bit and read cache
enabled is the inverse of the RCD bit, so you have a write through cache.
I think that notwithstanding the spec, most drives are write through (purely
because of the safety aspect). I suspect certain manufacturers use write back
caching to try to improve performance figures (at the expense of safety).
James
next prev parent reply other threads:[~2002-03-01 16:00 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-03-01 15:26 Dieter Nützel
2002-03-01 16:00 ` James Bottomley [this message]
-- strict thread matches above, loose matches on Subject: below --
2002-02-22 15:57 James Bottomley
2002-02-22 16:10 ` Chris Mason
2002-02-22 16:13 ` Stephen C. Tweedie
2002-02-22 17:36 ` James Bottomley
2002-02-22 18:14 ` Chris Mason
2002-02-28 15:36 ` James Bottomley
2002-02-28 15:55 ` Chris Mason
2002-02-28 17:58 ` Mike Anderson
2002-02-28 18:12 ` Chris Mason
2002-03-01 2:08 ` James Bottomley
2002-03-03 22:11 ` Daniel Phillips
2002-03-04 4:21 ` Jeremy Higdon
2002-03-04 5:31 ` Daniel Phillips
2002-03-04 6:09 ` Jeremy Higdon
2002-03-04 7:57 ` Daniel Phillips
2002-03-05 7:09 ` Jeremy Higdon
2002-03-05 22:56 ` Daniel Phillips
2002-03-04 16:52 ` Stephen C. Tweedie
2002-03-04 18:15 ` Daniel Phillips
2002-03-05 7:40 ` Jens Axboe
2002-03-05 22:29 ` Daniel Phillips
2002-03-12 7:01 ` Jens Axboe
2002-03-10 5:24 ` Douglas Gilbert
2002-03-11 11:13 ` Kurt Garloff
2002-03-12 6:58 ` Jens Axboe
2002-03-13 22:37 ` Peter Osterlund
2002-03-11 11:34 ` Stephen C. Tweedie
2002-03-11 17:15 ` James Bottomley
2002-03-12 1:17 ` GOTO Masanori
2002-03-04 14:48 ` James Bottomley
2002-03-06 13:59 ` Daniel Phillips
2002-03-06 14:34 ` James Bottomley
2002-03-04 3:34 ` Chris Mason
2002-03-04 5:05 ` Daniel Phillips
2002-03-04 15:03 ` James Bottomley
2002-03-04 17:04 ` Stephen C. Tweedie
2002-03-04 17:35 ` James Bottomley
2002-03-04 17:48 ` Chris Mason
2002-03-04 18:11 ` James Bottomley
2002-03-04 18:41 ` Chris Mason
2002-03-04 21:34 ` Stephen C. Tweedie
2002-03-04 18:09 ` Stephen C. Tweedie
2002-03-04 17:16 ` Chris Mason
2002-03-04 18:05 ` Stephen C. Tweedie
2002-03-04 18:28 ` James Bottomley
2002-03-04 19:55 ` Stephen C. Tweedie
2002-03-04 19:48 ` Daniel Phillips
2002-03-04 19:57 ` Stephen C. Tweedie
2002-03-04 21:06 ` Daniel Phillips
2002-03-05 14:58 ` Stephen C. Tweedie
2002-03-05 7:48 ` Jens Axboe
2002-03-04 19:51 ` Daniel Phillips
2002-03-05 7:42 ` Jens Axboe
2002-03-04 8:19 ` Helge Hafting
2002-03-04 14:57 ` James Bottomley
2002-03-04 17:24 ` Chris Mason
2002-03-04 19:02 ` Daniel Phillips
2002-03-05 7:22 ` Jeremy Higdon
2002-03-05 23:01 ` Daniel Phillips
2002-02-25 10:57 ` Helge Hafting
2002-02-25 15:04 ` James Bottomley
2002-02-21 23:30 Chris Mason
2002-02-22 14:19 ` Stephen C. Tweedie
2002-02-22 15:26 ` Chris Mason
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