Date: Thu, 18 Nov 1999 23:38:52 -0500 From: Simon Shapiro <shimon@simon-shapiro.org> To: Bernd Walter <ticso@cicely.de> Cc: Mattias Pantzare <pantzer@ludd.luth.se>, freebsd-fs@FreeBSD.ORG Subject: Re: RAID-5 and failure Message-ID: <3834D45C.1F963B3B@simon-shapiro.org> References: <ticso@cicely.de> <199911061716.SAA20783@zed.ludd.luth.se> <19991106183316.A9420@cicely7.cicely.de>
next in thread | previous in thread | raw e-mail | index | archive | help
Bernd Walter wrote: > > 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. 528. 512 data, 16 ECC for the sector. Nothing to do with RAID. > > -- > 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 -- Sincerely Yours, Shimon@Simon-Shapiro.ORG 404.664.6401 Simon Shapiro Unwritten code has no bugs and executes at twice the speed of mouth 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?3834D45C.1F963B3B>