From mboxrd@z Thu Jan 1 00:00:00 1970 From: joystick Subject: Re: RAID6 reshape integer problem Date: Wed, 08 Jan 2014 17:32:36 +0100 Message-ID: <52CD7DA4.4080608@shiftmail.org> References: <52C6B38E.8050804@turmel.org> <52C6EE49.2000907@turmel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Piotr Klimek Cc: Phil Turmel , linux-raid@vger.kernel.org List-Id: linux-raid.ids Had I seen this thread earlier... I would probably have responded that no, AFAIR it is not safe to reboot while reshaping (!) In fact i seem to recall that there was a very serious known problem during pivot_root , which is at the end of initramfs. A reshape in progress through that point would cause data loss. So the array could only be assembled after that point, so you had to modify initrd or use a livecd so to be sure that it wouldn't find/assemble the array at the early stages of boot. This is what I seem to remember. However by looking for details on such problem everywhere, I am not anymore able to find any reference. Does anybody recall this problem? Thanks J. On 08/01/2014 12:19, Piotr Klimek wrote: > Hi, > Everything works fine right now, all I have to do after reboot was > assemble array using backup file and set MDADM_GROW_ALLOW_OLD=1 > enviroment variable. > > Thanks for your help. > > 2014/1/3 Phil Turmel : >> It is supposed to be safe. With a clean shutdown, the superblock will >> have a record of the reshape progress and will be able to continue after >> re-assembly. >> >> But you'll probably have to assembly manually to specify the location of >> the critical section backup file. If your root FS is in this array, >> you'll have to intervene in the initramfs. >> >> HTH, >> >> Phil > >