From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Greaves Subject: Re: Proactive Drive Replacement Date: Tue, 21 Oct 2008 18:29:53 +0100 Message-ID: <48FE1191.3030302@dgreaves.com> References: <48FD94F9.3060400@dgreaves.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Mario 'BitKoenig' Holbe Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Mario 'BitKoenig' Holbe wrote: > David Greaves wrote: >> The main issue is that the drive being replaced almost certainly has a bad >> block. > > Then, the replacement is not pro-active ;) > >> This block could be recovered from the raid5 set but won't be. > > This is what 'check' and 'repair' operations > (/sys/block/md*/md/sync_action) can be used for. Well, yes and no. If I have a bad block then I could use the remaining disks to calculate data to overwrite it. So yes. However the overwrite may fail. So no. If I have an md managed mirror then the overwrite will write to the new disk and the old one. I don't care if the old one fails. David -- "Don't worry, you'll be fine; I saw it work in a cartoon once..."