From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: RAID5 won't mount after reducing disks from 8 to 6 Date: Thu, 17 Feb 2011 13:14:53 +1100 Message-ID: <20110217131453.39444287@notabene.brown> References: <20110217124214.00ad25dd@notabene.brown> <00E3AF11-6D18-4C5D-A165-56C86823A6D2@mac.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <00E3AF11-6D18-4C5D-A165-56C86823A6D2@mac.com> Sender: linux-raid-owner@vger.kernel.org To: Matt Tehonica Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Wed, 16 Feb 2011 20:47:08 -0500 Matt Tehonica wrote: > To be honest, I couldn't find good directions on how exactly to resize an array to be smaller so I put some bits and pieces together to do it. Guess I didn't understand everything beforehand because I didn't read anything about resizing the file system. I thought setting the "array-size" would take care of moving data before rebuilding onto the 6 disks. The next release of mdadm will be a bit more explicit in the man page about the need to resize the filesystem first - you aren't the first person to do this. > > Since I haven't resized the XFS filesystem, any recommendations on what to do next? Think it's possible to recover any of the data? For what it's worth, I haven't done anything to the 2 disks that I was going to remove. 8 to 6 disks in a RAID6 means 6 to 4 data disks, so 1/3 of the space is gone. And it really is gone, Little bits of it might be on the two devices that you were going to remove, but I doubt it would be usable, and it would be very hard to recover. So your best bet it to convince xfs_repair to work with what you've got and try to knit together as much as it can - which may be nothing, I really don't know. Maybe you could ask on an XFS list somewhere. But if you have any backups - I suggest they are by far your best bet. I'm sorry, but it isn't really possible for mdadm to detect that you haven't resized your filesystem and warn you about it :-( NeilBrown