From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH] scsi/sata write barrier support Date: Thu, 27 Jan 2005 18:00:41 -0500 Message-ID: <41F97299.2070909@pobox.com> References: <200501272242.j0RMgoP5016154@falcon30.maxeymade.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:39398 "EHLO parcelfarce.linux.theplanet.co.uk") by vger.kernel.org with ESMTP id S261262AbVA0XBQ (ORCPT ); Thu, 27 Jan 2005 18:01:16 -0500 In-Reply-To: <200501272242.j0RMgoP5016154@falcon30.maxeymade.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Doug Maxey , Jens Axboe Cc: Linux Kernel , Bartlomiej Zolnierkiewicz , linux-scsi@vger.kernel.org Doug Maxey wrote: > On Thu, 27 Jan 2005 13:02:48 +0100, Jens Axboe wrote: > >>Hi, >> >>For the longest time, only the old PATA drivers supported barrier writes >>with journalled file systems. This patch adds support for the same type >>of cache flushing barriers that PATA uses for SCSI, to be utilized with >>libata. > > > What, if any mechanism supports changing the underlying write cache? > > That is, assuming this is common across PATA and SCSI drives, and it is > possible to turn the cache off on the IDE drives, would switching the > cache underneath require completing the inflight IO? [ignoring your question, but it made me think...] I am thinking the barrier support should know if the write cache is disabled (some datacenters do this), and avoid flushing if so? Jeff