From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Farnsworth Subject: Re: Freeze after disabling write cache with hdparm -W0 /dev/sda Date: Wed, 11 Jul 2007 09:54:09 +0100 Message-ID: <46949AB1.80705@onelan.co.uk> References: <46935C4D.40003@onelan.co.uk> <4694669E.7060600@gmail.com> <46949555.9060208@onelan.co.uk> <469496A4.7070902@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from relay3.mail.uk.clara.net ([80.168.70.183]:40217 "EHLO relay3.mail.uk.clara.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752762AbXGKIyQ (ORCPT ); Wed, 11 Jul 2007 04:54:16 -0400 In-Reply-To: <469496A4.7070902@gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tejun Heo Cc: linux-ide@vger.kernel.org Tejun Heo wrote: > Simon Farnsworth wrote: >> Just a thought; is it possible to trigger libata EH from userspace? If >> so, we could write a small utility to disable write cache, then force EH >> to detect the change. > > That's automatically done. libata snoops cache on/off and triggers > revalidation but you can request manual rescan by echoing "- - -" to > /sys/class/scsi_host/hostX/scan. > Would it be worth changing our code to do "hdparm -W1 /dev/sda && hdparm -W0 /dev/sda", or would this not show anything. The lack of revalidation on some drives is what's worrying me a little here. -- Simon Farnsworth