From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: raid6 rebuild Date: Thu, 05 Apr 2007 09:54:14 -0400 Message-ID: <4614FF86.3020007@tmr.com> References: <20070404194638.GB3712@xi.wantstofly.org> <20070405055030.GA6978@xi.wantstofly.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20070405055030.GA6978@xi.wantstofly.org> Sender: linux-raid-owner@vger.kernel.org To: Lennert Buytenhek Cc: Dan Williams , mingo@redhat.com, neilb@suse.de, linux-raid@vger.kernel.org List-Id: linux-raid.ids Lennert Buytenhek wrote: > On Wed, Apr 04, 2007 at 08:22:00PM -0700, Dan Williams wrote: > > >>> While my RAID6 array was rebuilding after one disk had failed (which >>> I replaced), a second disk failed[*], and this caused the rebuild >>> process to start over from the beginning. >>> >>> Why would the rebuild need to start over from the beginning in this >>> case? Why couldn't it just continue from where it was? >>> >> I believe it is because raid5 and raid6 share the same error handler >> which sets MD_RECOVERY_ERR after losing any disk. It should probably >> not set this flag in 1-disk lost raid6 case, but I might be >> overlooking something else. >> > > Right, so you're saying that it's probably a bug rather than an > intentional 'feature'? No, I would say it's a "reviewable design decision" To be pedantic (as I often am), a bug really means that unintended results are generated. In this case I think the code functions as intended, but might be able to safely take some other action. I confess, I would feel safer with my data if the rebuild started over, I would like to be sure that when it (finally) finishes the data are valid. If you replaced the 2nd drive, then a full rebuild would be required in any case, to get ALL drives valid. -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979