From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean-Baptiste Thomas Subject: Re: Re: Paranoid mode for RAID-1 ? Date: Mon, 27 Apr 2015 12:18:09 +0200 (CEST) Message-ID: <743316986.23005258.1430129889889.JavaMail.zimbra@laposte.net> References: <972437107.22507366.1430116679975.JavaMail.zimbra@laposte.net> <4ADD42F9-407A-4266-A1FC-B92F3D46C36F@insync.za.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4ADD42F9-407A-4266-A1FC-B92F3D46C36F@insync.za.net> Sender: linux-raid-owner@vger.kernel.org To: Pieter De Wit Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 2015-04-27 20:45 +1200, Pieter De Wit wrote: > Sorry for jumping in late - but let's say it does "work" and a > drive returns an error, is that data lost ? Or which drive is > "right"? (Assuming that by "returns an error", you mean succeeds but the data does not no match what the other(s) returned.) Let's say there is a setting for how many components must agree. If they're not unanimous, read all the other components and look for a majority. The components in the minority are flagged faulty and the array is degraded but the read succeeds. If there is no majority, retry a few times. If a majority is found, all components which ever were in the minority are flagged faulty and the array is degraded but the read succeeds. If no majority is found, degrade all components, fail the read and stop the array. Or whatever is needed to prevent all further writes to this array and let the user investigate.