From owner-freebsd-hackers Fri Nov 28 21:51:32 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id VAA06501 for hackers-outgoing; Fri, 28 Nov 1997 21:51:32 -0800 (PST) (envelope-from owner-freebsd-hackers) Received: from dfw-ix3.ix.netcom.com (dfw-ix3.ix.netcom.com [206.214.98.3]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id VAA06496 for ; Fri, 28 Nov 1997 21:51:28 -0800 (PST) (envelope-from jerry_hicks@bigfoot.com) Received: (from smap@localhost) by dfw-ix3.ix.netcom.com (8.8.4/8.8.4) id XAA17571 for ; Fri, 28 Nov 1997 23:50:50 -0600 (CST) Received: from atl-ga15-03.ix.netcom.com(204.32.174.99) by dfw-ix3.ix.netcom.com via smap (V1.3) id rma017558; Fri Nov 28 23:50:44 1997 Message-ID: <347FAD4B.D1E682A@bigfoot.com> Date: Sat, 29 Nov 1997 00:51:07 -0500 From: Jerry Hicks Reply-To: jerry_hicks@bigfoot.com Organization: TerraEarth X-Mailer: Mozilla 4.04 [en] (X11; I; FreeBSD 2.2.5-STABLE i386) MIME-Version: 1.0 To: hackers@freebsd.org Subject: Re: Drive Mirroring References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk Jamil J. Weatherbee wrote: > > I have two exact duplicate drives and I want the second (sd1) to be an > exact duplicate of the first. Unfortunately ccd doesn't work here because > the drives aren't bootable, you cannot install on ccd drives from the cds > etc. One way to accomplish this is to go to single-user, sync, and then > dd if=/dev/sd0 of=/dev/sd1 bs=1024k. Unfortunately using this method on a > running system probably will corrupt the hell out of the copied over > filesystem. I've also tried using dump, but for these 4.3 giggers it > takes about 2 hours every night to remake filesystems on the second drive > and dump | restore to it. Can anyone think of a way I could maintain an > entire mirrored system without ccd, perhaps some software that nightly > looks at the changes on one drive and puts them over to the second without > basically rewriting the whole thing. Using QNX, we developed a cellular switch which boots from a flash 'disk'. A ram disk is created and the root filesystem is created there. The contents of the root filesystem are extracted from a gzipped archive on the flash before entering userland. An unused byte of the memory in the CMOS clock chip is used to save a persistent status code indicating whether to boot in operational, faulted, or service modes. You can get flash for a PC in several forms, including PCMCIA adapters for widely available flash cards. We used ZiaTech hardware which features user-writable flash integrated on the CPU board. IMO, this sort of configuration would be pretty neat to have for a FreeBSD net server. It alleviates a lot of the concerns one might deploying a high-availability system. Software upgrades are a snap too. We do ours remotely (worldwide from Memphis, TN). I don't specifically know how to work out the FreeBSD swapping related issues. Don't think it would be much though (?) Off to www.dejanews.com... Good Luck, Jerry Hicks jerry_hicks@bigfoot.com