Date: Sat, 17 Apr 2004 01:31:49 +1000 (EST) From: Bruce Evans <bde@zeta.org.au> To: "David O'Brien" <obrien@freebsd.org> Cc: cvs-src@freebsd.org Subject: Re: cvs commit: src/sbin/dump dump.8 dump.h main.c tape.csrc/sbin/restore extern.h main.c restore.8 tape.c Message-ID: <20040417011735.N14463@gamplex.bde.org> In-Reply-To: <20040416150742.GA16010@dragon.nuxi.com> References: <200404130258.i3D2w7WC034439@repoman.freebsd.org> <20040416150742.GA16010@dragon.nuxi.com>
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On Fri, 16 Apr 2004, David O'Brien wrote: > On Mon, Apr 12, 2004 at 07:58:07PM -0700, Brian Feldman wrote: > > green 2004/04/12 19:58:07 PDT > > > > FreeBSD src repository > > > > Modified files: > > sbin/dump dump.8 dump.h main.c tape.c > > sbin/restore extern.h main.c restore.8 tape.c > > Log: > > Add -P arguments for dump(8) and restore(8) which allow the user to > > use backup methods other than files and tapes. The -P argument is > > a normal sh(1) pipeline with either $DUMP_VOLUME or $RESTORE_VOLUME > > defined in the environment, respectively. > > Why do you need an option for this? Can't you just use 'dump ... |' and > '... | restore'? A simple pipeline can't handle media-change stuff well. Minix has a "vol" command which handles media changes for piped data. The media size is fixed and specified on the command line (typical usage was "tar ... | vol 360 /dev/fd0" for 360K floppies (remember them?)). This could be generalized to take a -P option much like dump now does (tar ... | vol -P ...). I don't know if dump needs to know more about media boundaries than can be handled in this way. A robust backup format would involve metadata at the start of each volume, and that is another thing that can'r be handled by a simple pipeline with the main generator of the data not knowing that it is writing to a fake large volume that actually consists of multiple volumes concatenated externally. Bruce
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