From mboxrd@z Thu Jan 1 00:00:00 1970 From: keld@keldix.com Subject: Re: [RFE] Please, add optional RAID1 feature (= chunk checksums) to make it more robust Date: Wed, 18 Jul 2012 13:49:35 +0200 Message-ID: <20120718114935.GA29915@www5.open-std.org> References: <17025a94-1999-4619-b23d-7460946c2f85@zmail15.collab.prod.int.phx2.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Jaromir Capik Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Wed, Jul 18, 2012 at 07:01:48AM -0400, Jaromir Capik wrote: > Hello. > > I'd like to ask you to implement the following ... > > The current RAID1 solution is not robust enough to protect the data > against random data corruptions. Such corruptions usually happen > when an unreadable sector is found by the drive's electronics > and when the drive's trying to reallocate the sector to the spare area. > There's no guarantee that the reallocated data will always match > the original stored data since the drive sometimes can't read the data > correctly even with several retries. That unfortunately completely masks > the issue, because the sector can be read by the OS without problems > even if it doesn't contain correct data. Would it be possible > to implement chunk checksums to avoid such data corruptions? > If a corrupted chunk is encountered, it would be taken from the second > drive and immediately synced back. This would have a small performance > and capacity impact (1 sector per chunk to minimize performance impact > caused by unaligned granularity = 0.78% of the capacity with 64k chunks). > > Please, let me know if you find my request reasonable or not. I believe alternative to that is implemented via the Linux RAID MD badblock feature. best regards keld