From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Boldi Subject: Re: [PATCH RFC 3/4] md: writeback caching policy for raid5 [experimental] Date: Thu, 12 Apr 2007 08:37:43 +0300 Message-ID: <200704120837.43898.a1426z@gawab.com> References: <20070411055729.15745.51513.stgit@dwillia2-linux.ch.intel.com> <20070411060036.15745.7016.stgit@dwillia2-linux.ch.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20070411060036.15745.7016.stgit@dwillia2-linux.ch.intel.com> Content-Disposition: inline Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Dan Williams wrote: > In write-through mode bi_end_io is called once writes to the data disk(s) > and the parity disk have completed. > > In write-back mode bi_end_io is called immediately after data has been > copied into the stripe cache, which also causes the stripe to be marked > dirty. This is not really meaningful, as this is exactly what the page-cache already does before being synced. It may be more reasonable to sync the data-stripe as usual, and only delay the parity. This way you shouldn't have to worry about unclean shutdowns. Thanks! -- Al