From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mathias Mueller Subject: Re: broken raid level 5 array caused by user error Date: Tue, 10 Nov 2015 22:33:33 +0100 Message-ID: <3c05d813e42324cdf95989784f6d7b17@pingofdeath.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: Phil Turmel Cc: Linux raid List-Id: linux-raid.ids Hi Phil, >> This both combinations > > Well, I gave you *four* combinations for order, and two suggestions for > chunk size. Eight combinations to try. Sorry, this two words were just the beginning of a sentence, which I didn't finish an forgot to remove :) I tried 16 combinations at all (eight with --data-offset=1024 and eight with --data-offset=2048), the following four combinations gave the "/dev/md0 has unsupported feature(s)" message occurs: --data-offset=1024 --chunk 64: sde sdd sdb sdc --data-offset=1024 --chunk 512: sde sdd sdb sdc --data-offset=1024 --chunk 64: sde sdb sdd sdc --data-offset=1024 --chunk 512: sde sdb sdd sdc the other four combinations with --data-offset=1024 and all eight combinations with --data-offset=2048 gave fsck.ext2: Superblock invalid, trying backup superblocks... fsck.ext2: Bad magic number in super-block while trying to open /dev/md0 >> /dev/md0 has unsupported feature(s): FEATURE_C16 FEATURE_C17 >> FEATURE_C18 >> FEATURE_C19 FEATURE_C21 FEATURE_C22 FEATURE_C23 FEATURE_C25 >> FEATURE_C27 >> FEATURE_C28 FEATURE_I29 FEATURE_R29 >> e2fsck: Get a newer version of e2fsck! > > None of the feature bits are documented to exist. The choice of first > drive must be wrong. oh that's good to know >> Also mdadm --examine on on of the drives tells "Data offset: 2048 >> Sectors" when mdadm --create --data-offset 1024 is used. Is this >> normal? >> It's confusing me (using --data-offset 2048 on creation gives "Data >> offset: 2048 Sectors"). > > mdadm must be enforcing a minimum offset. is it possible that the data-offset differs from device to device? Thanks Mathias