From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Robinson Subject: Check/repair RAID-5 with hints? Date: Fri, 02 Apr 2010 12:49:05 +0100 Message-ID: <4BB5D9B1.8070000@anonymous.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: Linux RAID List-Id: linux-raid.ids I have just replaced one of the drives in my RAID-5 array which was showing offline uncorrectable and current pending sectors. I took the system down into single-user mode, failed the disc out of the array, dd_rescue'd the disc to a fresh one, and added the new disc back into the array. During the dd_rescue, 68k of 1TB failed, about 1MB from the end of the disc. My array has a write-intent bitmap so the resync was very quick. So now I have an active, theoretically synchronised RAID-5, and I know some 68k on one of the discs is likely rubbish. I would like to run some kind of scrub/check/repair on the relevant area, including a hint that it is one particular disc that is wrong. Is this possible? I have CentOS 5.4, kernel 2.6.18-164.15.1, mdadm 2.6.9, 0.90 metadata. I wish we had the hot-replace feature that was discussed on this list a wee while ago... I'm wondering if my best course of action is to fail the fresh disc out of the array again, dd the data off the offending area (it will be re-built from the good discs), write it again (so the write-intent bitmap is updated), and re-add the fresh disc to get that area re-synced onto the fresh disc. Cheers, John.