From owner-freebsd-questions Tue Jan 2 11:44:03 1996 Return-Path: owner-questions Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id LAA06002 for questions-outgoing; Tue, 2 Jan 1996 11:44:03 -0800 (PST) Received: from phaeton.artisoft.com (phaeton.Artisoft.COM [198.17.250.211]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id LAA05997 for ; Tue, 2 Jan 1996 11:44:01 -0800 (PST) Received: (from terry@localhost) by phaeton.artisoft.com (8.6.11/8.6.9) id MAA12378; Tue, 2 Jan 1996 12:34:55 -0700 From: Terry Lambert Message-Id: <199601021934.MAA12378@phaeton.artisoft.com> Subject: Re: NETBSD ccd driver To: eblood@winky.reno.nv.us (Eric Blood) Date: Tue, 2 Jan 1996 12:34:54 -0700 (MST) Cc: questions@FreeBSD.org In-Reply-To: <199512292120.NAA00944@winky.reno.nv.us> from "Eric Blood" at Dec 29, 95 01:20:47 pm X-Mailer: ELM [version 2.4 PL24] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-questions@FreeBSD.org Precedence: bulk > What is the NetBSD ccd driver? ConCatenated Disk driver. It takes several drives, and makes them look like one drive. With the devfs code in -current, there is a much cleaner way to implement this sort of thing. It's much more general, as well, so you could use the full implementation to fix the disklabel and OS compatability issues (magically). These are all instances of volume spanning and logical volume management. I don't recommend ccd or striping unless you need it for some serious application that you can't do any other way. You end up with a much lower MTBF on the spanned drives. If you had three drives, your MTBF will be: min(min(MTBF1,MTBF2),MTBF3) --------------------------- 3 Divide the one drive MTBF by the number of drives for identical drives. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.