From owner-freebsd-questions Wed Sep 15 22:11:44 1999 Delivered-To: freebsd-questions@freebsd.org Received: from posgate.acis.com.au (posgate.acis.com.au [203.14.230.14]) by hub.freebsd.org (Postfix) with ESMTP id 753B314A08 for ; Wed, 15 Sep 1999 22:11:38 -0700 (PDT) (envelope-from andymac@bullseye.apana.org.au) Received: from bullseye.apana.org.au (uucp@localhost) by posgate.acis.com.au (8.9.2/8.9.2/Debian/GNU) with UUCP id PAA07834; Thu, 16 Sep 1999 15:04:17 +1000 (EST) Received: from bullseye.apana.org.au (central.apana.org.au [203.9.107.245]) by bullseye.apana.org.au (8.8.8/8.8.8) with SMTP id HAA03929; Thu, 16 Sep 1999 07:51:13 +1000 (EST) (envelope-from andymac@bullseye.apana.org.au) Date: Thu, 16 Sep 1999 07:48:33 +1000 (EST) From: Andrew MacIntyre To: Andriss Cc: questions@FreeBSD.ORG Subject: SCSI drive mirroring (was Vinum Concerns) In-Reply-To: Message-ID: X-X-Sender: andymac@bullseye.apana.org.au MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Wed, 15 Sep 1999, Andriss wrote: > Yes the drives are absolutely identical (u2w SCSI: IBM UltraStar 18es) {...} > Can you tell me what parameters I should use with dd? Reading the > manual page is think this should be used: > > dd if=/dev/rda0 of=/dev/rda1 > > Important assumption: da0 is source, and da1 is destination. That's what I'd be using, at least initially. Its possible that you could use a larger block size (bs=) to improve performance, but verify it works first! > ...And what do you mean watch out for effects of open files? > Could you explain that one please? Given the way you phrased the original question, I was assuming that the source drive would be your boot drive, and probably be home to various active log files. I was cautioning to be aware, just as you should be with all methods of backup used with raw devices which have filesystems mounted from them, that the state you are backing up may not be 100% consistent. Particularly in this case, where you may find that the mirrored drive contains partitions that get fsck'ed when you try and use them. There are ways to reduce the likelihood of significant problems, such as shutting down non-essential services for the duration of the backup, and using "sync" before copying. This is where a lower level mirroring solution like vinum makes life easier. > (and is there a way to list all open files?) lsof (in ports IIRC). -- Andrew I MacIntyre "These thoughts are mine alone..." E-mail: andrew.macintyre@aba.gov.au (work) | Snail: PO Box 370 andymac@bullseye.apana.org.au (play) | Belconnen ACT 2616 Fido: Andrew MacIntyre, 3:620/243.18 | Australia To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message