From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-15?Q?Stefan_/*St0fF*/_H=FCbner?= Subject: Re: --assume-clean on raid5/6 Date: Sat, 07 Aug 2010 14:28:55 +0200 Message-ID: <4C5D5187.7080109@stud.tu-ilmenau.de> References: Reply-To: st0ff@npl.de Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: brian.foster@emc.com Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi Brian, --assume-clean skips over the initial resync. Which - if you will create a filesystem after creating the array - is a time-saving idea. But keep in mind: even if the disks are brand new and contain only zeros, the parity would probably look not all zeros. So reading from such an array would be a bad idea. But if the next thing you do is create LVM/filesystem etc., then all bit read from the array will have been written to before (and by that are in sync). Stefan Am 06.08.2010 03:19, schrieb brian.foster@emc.com: > Hi all, > > I've read in the list archives that use of --assume-clean on raid5 > (raid6?) is not safe assuming the member drives are not sync, but it's > not clear to me as to why. I can see the content of an written raid5 > array change if I fail a drive out of the array (created w/ > --assume-clean), but data that I write prior to failing a drive remains > intact. Perhaps I'm missing something. Could somebody elaborate on the > danger/risk of using --assume-clean? Thanks in advance. > > Brian > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html