From mboxrd@z Thu Jan 1 00:00:00 1970 From: hpa@zytor.com (H. Peter Anvin) Subject: Re: Call for RAID-6 users Date: Fri, 30 Jul 2004 15:58:34 +0000 (UTC) Sender: linux-raid-owner@vger.kernel.org Message-ID: References: <20040726213811.GA17363@jim.sh> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Followup to: <20040726213811.GA17363@jim.sh> By author: Jim Paris In newsgroup: linux.dev.raid > > > Thus, if you have used RAID-6 and have good or bad experiences, I'd > > like to know them as soon as possible. > > Just tried setting up a RAID-6 on a new server, and I'm seeing > complete filesystem corruption. > > I have 6 250GB disks, and want them all in the array. I've created it > degraded, with the first disk missing, since that disk temporarily > holds the system. > > Using kernel 2.6.7, mdadm 1.6.0, I did something like this: > > # mdadm --create /dev/md1 --level=6 --chunk=128 --raid-devices=6 missing /dev/hd{g,i,k,m,o}2 > > which gives me: > > md1 : active raid6 hdo2[5] hdm2[4] hdk2[3] hdi2[2] hdg2[1] > 976269312 blocks level 6, 128k chunk, algorithm 2 [6/5] [_UUUUU] > Okay, found the messages... Can you create failures by creating a full array and then fail out drives? That would rule out problems with the way mdadm creates the array. **** When the array is just created, it's not synchronized!!! **** Thus, when the array is first created it needs to finish synchronizing before it's usable. My current guess based on what I've seen so far is that it's a bug in mdadm in creating arrays with exactly 1 missing drive, as opposed to a kernel bug. -hpa