From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: RAID5 reconstruction ? Date: Sat, 30 May 2009 14:39:53 -0400 Message-ID: <4A217D79.9070006@tmr.com> References: <37d33d830905292244w685499b3h391aa2ca7a5b1ad@mail.gmail.com> <4A213612.7080206@anonymous.org.uk> <1243699735.5740.103.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1243699735.5740.103.camel@localhost> Sender: linux-raid-owner@vger.kernel.org To: Redeeman Cc: John Robinson , SandeepKsinha , Linux RAID List-Id: linux-raid.ids Redeeman wrote: > On Sat, 2009-05-30 at 14:35 +0100, John Robinson wrote: > >> On 30/05/2009 06:44, SandeepKsinha wrote: >> >>> Hi all, >>> >>> Say If I have a RAID 5 array of 50GB of five disks of 10GB each. >>> >>> I have data of 5GB. When a disk fails and replaced with a spare disk. >>> Will the reconstruction happen only for the 5GB allocated disk blocks >>> or it will happen for the whole disk size. >>> >> The whole disc size, for now anyway; md does not currently note which >> blocks have been used by its client (the filesystem, LVM, whatever). >> >> >>> Is it possible to make reconstruction intelligent enough to keep it optimized ? >>> >> This has been discussed in combination with supporting SSD drives' TRIM >> function, and would mean md had to keep track of used chunks or possibly >> even sectors using a bitmap or something like that, but whether anyone's >> working on it I don't know. >> > > I would say it should be possible to 'query' the filesystem for that > information. Obviously this will only work if you run a filesystem on it > which supports it, but it would seem like a nicer solution than a bitmap > for it. > There is a program which does that, but i think it was for ext2. Read the inodes and saved the data. I believe 'dump' does something similar, but it's on a file system basis and I don't recall (or care much about) the details. -- bill davidsen CTO TMR Associates, Inc "You are disgraced professional losers. And by the way, give us our money back." - Representative Earl Pomeroy, Democrat of North Dakota on the A.I.G. executives who were paid bonuses after a federal bailout.