Date: Sun, 04 Nov 2012 16:56:58 -0800 From: "Ronald F. Guilmette" <rfg@tristatelogic.com> To: freebsd-questions@freebsd.org Subject: Questions about dump/restore to/from DVD media Message-ID: <20880.1352077018@tristatelogic.com>
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I would like to make a backup of one of my systems using dump(8) in order to be sure that I get everything, including all of the obscure file attribute bits. I would like to make this backup to a _minimal_ number of DVD+R disks. What's the proper procedure for this? In the dump(8) man page, I see the following example: /sbin/dump -0u -L -C16 -B4589840 -P 'growisofs -Z /dev/cd0=/dev/fd/0' /u There are several problems with this example, as far as I am concerned. First I have no particular interest in, or need for _either_ an ISO 9660 _or_ a UDF file system on my backup media. And in fact, that seems to me as if it is likely to be an utter waste of (precious) space on the backup media. Can't I just put the output of the dump command _directly_ onto the output DVD+R media? If so, how would I do this? Would a command such as the following work? /sbin/dump -0u -L -C16 -B4589840 -P 'dd of=/dev/acd0 bs=2048' /u If not, why not? (I already know for sure that I can _read_ everything off of a DVD+R using just dd, so it seems logical that I should likewise be able to write an entire CD using just dd, but I suspect that there may be more to it that this, since I've never seen any references or examples anywhere of anybody writing either CDs or DVDs using dd.) Actually, I just noticed in the dump manpage the -f option. So would this work in place of the above command line? /sbin/dump -0u -L -C16 -B4589840 -f /dev/acd0 /u And if THAT works, then can dump properly sense the actual end-of-media on /dev/acd0, so that the -B option can just be ommitted? Another issue is that I most definitely want to use an absolute minimum of DVD+Rs to store the dump. So I am wondering how I might be able to wedge gzip into this whole process. Could I do something like this? If not, why not? /sbin/dump -0u -L -C16 -B4589840 -P 'gzip | dd of=/dev/acd0 bs=2048' /u Lastly, I want to make a backup of one entire _system_... not just one of the several partitions that compose that system. How exactly can I do this? I mean sure, I can back up each partition separately, using dump, one at a time, but if I do that then the logical implication would seem to be that on the last DVD+R used to make a backup of each of the partitions, there could possibly be a lot of unused/wasted space which could have been used to store the first part of the dump for the next partition in turn. Is there any way to effectively deal with _this_ issue? Regards, rfg
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