Date: Sat, 6 Nov 1999 18:33:16 +0100 From: Bernd Walter <ticso@cicely.de> To: Mattias Pantzare <pantzer@ludd.luth.se> Cc: Bernd Walter <ticso@cicely.de>, freebsd-fs@FreeBSD.ORG Subject: Re: RAID-5 and failure Message-ID: <19991106183316.A9420@cicely7.cicely.de> In-Reply-To: <199911061716.SAA20783@zed.ludd.luth.se> References: <ticso@cicely.de> <199911061716.SAA20783@zed.ludd.luth.se>
next in thread | previous in thread | raw e-mail | index | archive | help
On Sat, Nov 06, 1999 at 06:16:47PM +0100, Mattias Pantzare wrote: > > On Sat, Nov 06, 1999 at 04:58:55PM +0100, Mattias Pantzare wrote: > > > What hapens if the data part of a write to a RAID-5 plex completes but not the > > > parity part (or the other way)? > > > > > The parity is not in sync - what else? > > The system could detect it and recalculate the parity. Or give a warning to > the user so the user knows that the data is not safe. That's not possible because you need to write more then a single sector to keep parity in sync which is not atomic. In case one of the writes fail vinum will do everything needed to work with it and to inform the user. Vinum will take the subdisk down because such drives should work with write reallocation enabled and such a disk is badly broken if you receive a write error. If the system panics or power fails between such a write there is no way to find out if the parity is broken beside verifying the complete plex after reboot - the problem should be the same with all usual hard and software solutions - greg already begun or finished recalculating and checking the parity. I asume that's the reason why some systems use 520 byte sectors - maybe they write timestamps or generationnumbers in a single write within the sector. -- B.Walter COSMO-Project http://www.cosmo-project.de ticso@cicely.de Usergroup info@cosmo-project.de To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?19991106183316.A9420>