From owner-freebsd-fs Thu Nov 18 20:38:56 1999 Delivered-To: freebsd-fs@freebsd.org Received: from nomis.simon-shapiro.org (nomis.simon-shapiro.org [209.86.126.163]) by hub.freebsd.org (Postfix) with SMTP id 1ABA2155BF for ; Thu, 18 Nov 1999 20:38:53 -0800 (PST) (envelope-from shimon@simon-shapiro.org) Received: (qmail 99725 invoked from network); 19 Nov 1999 04:38:52 -0000 Received: from localhost.simon-shapiro.org (HELO simon-shapiro.org) (127.0.0.1) by localhost.simon-shapiro.org with SMTP; 19 Nov 1999 04:38:52 -0000 Message-ID: <3834D45C.1F963B3B@simon-shapiro.org> Date: Thu, 18 Nov 1999 23:38:52 -0500 From: Simon Shapiro Organization: Simon's Garage X-Mailer: Mozilla 4.6 [en] (X11; I; FreeBSD 3.3-STABLE i386) X-Accept-Language: en-US MIME-Version: 1.0 To: Bernd Walter Cc: Mattias Pantzare , freebsd-fs@FreeBSD.ORG Subject: Re: RAID-5 and failure References: <199911061716.SAA20783@zed.ludd.luth.se> <19991106183316.A9420@cicely7.cicely.de> Content-Type: text/plain; charset= Content-Transfer-Encoding: 7bit Sender: owner-freebsd-fs@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org 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