From owner-freebsd-questions@FreeBSD.ORG Wed Sep 30 03:03:10 2009 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 32B08106566B for ; Wed, 30 Sep 2009 03:03:10 +0000 (UTC) (envelope-from freebsd@edvax.de) Received: from mx02.qsc.de (mx02.qsc.de [213.148.130.14]) by mx1.freebsd.org (Postfix) with ESMTP id CBE1E8FC19 for ; Wed, 30 Sep 2009 03:03:09 +0000 (UTC) Received: from r55.edvax.de (port-92-195-71-245.dynamic.qsc.de [92.195.71.245]) by mx02.qsc.de (Postfix) with ESMTP id 8D18B219A7; Wed, 30 Sep 2009 05:02:28 +0200 (CEST) Received: from r55.edvax.de (localhost [127.0.0.1]) by r55.edvax.de (8.14.2/8.14.2) with SMTP id n8U32R03009022; Wed, 30 Sep 2009 05:02:27 +0200 (CEST) (envelope-from freebsd@edvax.de) Date: Wed, 30 Sep 2009 05:02:27 +0200 From: Polytropon To: PJ Message-Id: <20090930050227.5b75c453.freebsd@edvax.de> In-Reply-To: <4AC2C104.7090206@videotron.ca> References: <4AC29BE6.4000505@videotron.ca> <20090930023051.cff2b0b4.freebsd@edvax.de> <4AC2C104.7090206@videotron.ca> Organization: EDVAX X-Mailer: Sylpheed 2.4.7 (GTK+ 2.12.1; i386-portbld-freebsd7.0) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org Subject: Re: backups & cloning X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Polytropon List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 30 Sep 2009 03:03:10 -0000 On Tue, 29 Sep 2009 22:23:00 -0400, PJ wrote: > I feel a bit stupid, as usual, my carelessness led me to miss the > difference between ad1 and ad2... dumb, dumb, dumb. As long as you realize it BEFORE any writing operation, it's no problem. Keep in mind that the numbering of ad*, as well as of da* (which your USB disk will probably show up as) depends on the position of the drive on the ATA controller, e. g. primary master -> /dev/ad0 primary slave -> /dev/ad1 secondary master -> /dev/ad2 secondary slave -> /dev/ad3 ... This numbering sceme even does take place if you're using the master channels only, so in this example you would have the ad0 and ad2 drives, no matter if ad1 is present or not. > But... 2 questions: > 1. will the s1a slice dump the entire system, that is, the a, d, e, f > and g slices or is it partitions? As far as I remember, you cannot dump slices. You can dump partitions only, or, in other words, the dump program does operate on file systems (and those are represented by one partition per file system). If you want to duplicate slice-wise, dd should be used, such as the following example: # dd if=/dev/ad0s1 of=/mnt/usb/slice1.dd bs=1m If you want to duplicate partition-wise, you need to dump and restore each partition, just as my verbose example showed. > I've been very confused with the slices/partitions. The term slice refers to what MICROS~1 calls "DOS primary partitions" in the widest sense. Due to DOS limitations, PCs do only support 4 slices per disk. The term partition refers to a sub-area inside a FreeBSD slice. Partitions can be used to separate functional subtrees partition-wise. Of course, I often see settings where there's only one partition on the slice, that's a common thing. > I meant above, to dump the whole slice - but I guess that it has to be > done with the partitions. Partitions: use dump + restore Slices: use dd Whole disks: use dd > and when I do dump -0Laf /dev /ad1s1a /dev/da0s1a > the errors are > "write error 10 blocks into volume 1 > do you want to restart:" Okay, everything is clear now. Just "interpret" the dump command: dump full snapshot autosize output=/dev /ad1s1a First of all, /ad1s1a does not exist. Then, /dev/da0s1a is ignored. The command doesn't make sense. The syntax of dump can be simplified as follows: dump (other options) -f outputfile inputdevice Note that outputfile can be - (the standard output) which can then be redirected somewhere else. At this position, I need to ask you: What are you trying to do? a) I want to dump ad1s1a as it is onto the disk that is da0. b) I want to dump ad1s1a as a file on the disk that is da0. Let's take a) first. I assume you have prepared the disk da0 as shown in my earlier example, or you simply have used sysinstall to create a slice on the disk and partitions inside the slice that are big enough to hold the data you want to transfer to them. Check their existance: # ll /dev/ad0* /dev/da0* The listing should give you similar slices and partitions both for the source and the target disk. First you mount the target disk and change the working directory to it: # mount /dev/da0s1a /mnt # cd /mnt Now you dump from your ad0 disk to where you currently are: # dump -0 -L -a -u -f - /dev/ad0s1a | restore -r -f - Proceed with the other partitions. Mount them, change into their mountpoints that are now relative to /mnt (e. g. /mnt/var, /mnt/home) and repeat this command, substituting the source /dev/ad0s1[defg]. Finally, change back to / and umount everything in a successive way, sync, done. For case b) it's much easier. When you want to create data files, you don't need to slice / partition your USB disk, just newfs and mount it: # newfs /dev/da0 # mount /dev/da0 /mnt Now you can create all the data files for the different partitions: # dump -0 -L -a -u -f /mnt/root.dump /dev/ad0s1a # dump -0 -L -a -u -f /mnt/tmp.dump /dev/ad0s1d # dump -0 -L -a -u -f /mnt/var.dump /dev/ad0s1e # dump -0 -L -a -u -f /mnt/usr.dump /dev/ad0s1f # dump -0 -L -a -u -f /mnt/home.dump /dev/ad0s1g > The first time I tried with -L the error was 20 blocks... > Both the slices for dump from and to are same size (2gb) and certainly > not full by a long shot ( if I reccall correctly, only about 14% is used) As far as I see, the command line just was wrong. > why into SUM? The idea behind doing dump / restore in SUM is - in addition with unmounted partitions - to ensure that no write access disturbes the reading process from the partitions. Of course, it's possible to use -L and stay in MUM. > I'm really the only user and I usually stay as root???? It's valid to perform dump / restore as root. > if SUM, shouldn't the # below be $? No. The # indicates root permissions in any shell. The $ indicates non-root access in sh or bash, the same does % in csh. > So, ad1 is the target disk and ad0 is the source? I don't know your disk setup. :-) If you're booting from ad0 and want to duplicate THIS particular system, then this is your source. But you said that you want to use a USB disk as target, that would be da0 then. > I don't follow the next sequence... > after shutdown, boot in SUM? No. The command # shutdown now gets you into SUM. You can achieve this by rebooting and and issuing boot -s at the loader prompt, but why so complicated? :-) > the following commands ($ instead of # ?) would be on the source (ad0 ?) Correct. > What is happening with the umount commands below? It unmounts any partitions that aren't required for system operations (here: for dumping and restoring). If you use the -L flag for dump, this step isn't needed. > And the mount -r / ? This mounts / in read-only mode, because you can't unmount it, you need /sbin/dump, for example, so it should be reachable. > The fsck is to clean the partitions, right? Correct. BUT: If you don't umount the partitions and want to use -L as described above, don't fsck the partitions. The fsck should be run on unmounted partitions only. It's just to make sure that the partitions you want to dump are in good condition. SUMMARY: You don't need the SUM step. You don't need to unmount the partitions, but then you should not run fsck, and you should use -L for dump. -- Polytropon Magdeburg, Germany Happy FreeBSD user since 4.0 Andra moi ennepe, Mousa, ...