From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Robinson Subject: Re: RAID5 reconstruction ? Date: Sat, 30 May 2009 14:35:14 +0100 Message-ID: <4A213612.7080206@anonymous.org.uk> References: <37d33d830905292244w685499b3h391aa2ca7a5b1ad@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <37d33d830905292244w685499b3h391aa2ca7a5b1ad@mail.gmail.com> Sender: linux-raid-owner@vger.kernel.org To: SandeepKsinha Cc: Linux RAID List-Id: linux-raid.ids 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. Cheers, John.