linux-kernel - Re: [RFC PATCH] block: Change default IO scheduler to deadline except SATA

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Message-ID: <4F847DAB.5030707@kernel.dk>
Date:	Tue, 10 Apr 2012 20:36:27 +0200
From:	Jens Axboe <axboe@...nel.dk>
To:	Mike Snitzer <snitzer@...hat.com>
CC:	Vivek Goyal <vgoyal@...hat.com>,
	linux kernel mailing list <linux-kernel@...r.kernel.org>,
	martin.petersen@...cle.com
Subject: Re: [RFC PATCH] block: Change default IO scheduler to deadline except
 SATA

On 2012-04-10 18:13, Mike Snitzer wrote:
> That said, we can have a _very_ good hint that a SCSI device is a raid array if:
> 
> 1) optimal_io_size is not zero, minimum_io_size is not equal to
> optimal_io_size, and optimal_io_size is a multiple of minimum_io_size
> 
> 2) WCE=0 (higher-end arrays with a writeback cache)

Any other device than a basic SATA disk will have WCE=0. So I don't
think that gives you a very good hint of the nature of it,
unfortunately.

-- 
Jens Axboe

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