From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konstantin Svist Subject: Re: messed up changing chunk size Date: Mon, 19 Jul 2010 21:28:24 -0700 Message-ID: <4C4525E8.2010702@relevad.com> References: <4C439D19.4070906@gmail.com> <4C44939A.1060200@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4C44939A.1060200@gmail.com> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 07/19/2010 11:04 AM, Konstantin Svist wrote: > Just noticed that I got this in /var/log/messages when I sized it down: > Jul 18 12:00:44 slon kernel: md0: detected capacity change from > 900199022592 to 300066275328 > Jul 18 12:00:44 slon kernel: md0: unknown partition table > > And scraped from command line session: > > [root@slon ~]# cat /proc/mdstat > Personalities : [raid6] [raid5] [raid4] > md0 : active raid5 sdd1[3] sda4[0] sdc1[2] sdb1[1] > 879100608 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU] > [root@slon ~]# mdadm --grow -z 293033472 > --backup-file=/root/grow_md0_size.bak /dev/md0 > mdadm: component size of /dev/md0 has been set to 293033472K > [root@slon ~]# cat /proc/mdstat > Personalities : [raid6] [raid5] [raid4] > md0 : active raid5 sdd1[3] sda4[0] sdc1[2] sdb1[1] > 293033472 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU] > > Looks like instead of setting the number of blocks per-drive (as per > the man page), the -z option set the number of total blocks for the > array, instead. Which means I'm very thoroughly screwed. > > Right now I'm trying to reshape back to the old chunk size and will > then try to resize the array back to the previous size. If the chunk > size change and array resize are both fully reversible -- and I don't > think I'm THAT lucky -- then I might be able to get some stuff back. > Will see, I guess. Can someone confirm that this command should work to revert the size? mdadm --grow -z 879100608 --backup-file=/root/grow_md0_size_revert.bak /dev/md0