From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kasprzak Subject: Replacing a failed disk "in advance" Date: Wed, 20 May 2015 16:20:49 +0200 Message-ID: <20150520142049.GT24672@fi.muni.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hello, I have a RAID-5 volume of 8 physical disks. One of these disks failed the SMART self-test with an unreadable block error. Unfortunately I have discovered that there is _another_ bad block on another disk. It is a different block, so the RAID-5 volume as a whole is still working. But as a whole, the RAID-5 volume has at least two unreadable sectors on two different disks. What is the best way to replace these two failing disks one by one without the loss of data? I cannot mdadm --fail one of them, because the subsequent rebuild on a new disk would fail on reading the other bad block. I would like to add the ninth drive to the RAID-5 volume, and put a replica of one of the failing drives to it. Then remove the just-replicated drive, and do the same with the other failing drive. Thanks, -Yenya -- | Jan "Yenya" Kasprzak | | New GPG 4096R/A45477D5 -- see http://www.fi.muni.cz/~kas/pgp-rollover.txt | | http://www.fi.muni.cz/~kas/ Journal: http://www.fi.muni.cz/~kas/blog/ | Smart data structures and dumb code works a lot better than the other way around. --Eric S. Raymond