From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Forrest Subject: Recovery Optimization? Date: Fri, 18 Feb 2011 16:06:43 -0800 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids I'm just learning how the md system works so what I'm going to say might not be sensible. I read that if a disk in a RAID5 set goes bad, and the disk is replaced by a new one, that the recovery operation takes place blindly. By this I mean that all the stripes will be read so that new parity blocks can be written. But, there might be stripes that contain only blocks that aren't used by the filesystem. Wouldn't it be good when doing recovery if some kind of allocation map were created so that unused stripes wouldn't be restored. I would think that depending on how full the disk is that this could save time. Is this reasonable? Cordially, -- Jon Forrest Research Computing Support College of Chemistry 173 Tan Hall University of California Berkeley Berkeley, CA 94720-1460 510-643-1032 jlforrest@berkeley.edu