From owner-freebsd-hackers Fri Feb 27 19:28:09 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id TAA04293 for freebsd-hackers-outgoing; Fri, 27 Feb 1998 19:28:09 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from sendero.simon-shapiro.org (sendero-fxp0.Simon-Shapiro.ORG [206.190.148.34]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id TAA04269 for ; Fri, 27 Feb 1998 19:28:01 -0800 (PST) (envelope-from shimon@sendero-fxp0.simon-shapiro.org) Received: (qmail 18411 invoked by uid 1000); 28 Feb 1998 03:36:02 -0000 Message-ID: X-Mailer: XFMail 1.3-alpha-021598 [p0] on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: <19980228134228.40320@freebie.lemis.com> Date: Fri, 27 Feb 1998 19:36:02 -0800 (PST) Reply-To: shimon@simon-shapiro.org Organization: The Simon Shapiro Foundation From: Simon Shapiro To: Greg Lehey Subject: Re: SCSI Bus redundancy... Cc: hackers@FreeBSD.ORG, blkirk@float.eli.net, jdn@acp.qiv.com, Wilko Bulte Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On 28-Feb-98 Greg Lehey wrote: ... >> DPT arrays? Simple; you make an ioctl call into the DPT driver, I >> write a message to the controler, specifying which disk to add to >> which array, the controller starts a hot rebuild, etc. The details >> escape me right now, but I belive it is doable. Why would you want >> to do that? No idea... :-) > > I was thinking more about what the ioctl call does. Raid 5 spreads > data in stripes over all drives (or subdisks if you're using a > Veritas-like volume manager). Add a drive, and you break this > mapping. The only way to rearrange is to rewrite all the disks. Is > that what they do? Or are they cheating in some manner? ( At some point in this thread MarkS (from DPT) is going to enter the thread and either explain it properly or tell me to stop violating the NDA I so cleverly signed :-) the IOCTL does nothing more than package a SCSI command, ship it to the controller, wait for the reply and ship that back. The rest is done in the controller. I do not think it re-writes the whole disk array. there is no real need for that. I think there is some hardware support for some of this stuff, and that DPT people know few things I do not. Once I clear my desk of what I am messing up now, I'll look into it a bit better. Simon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message