Subject: Re: Today's Un*x lesson
To: Dave Burgess <firstname.lastname@example.org>
From: Mark P. Gooderum <email@example.com>
Date: 06/20/1994 22:45:52
According to Dave Burgess:
> Today's BSD Lesson:
> There is a big difference between:
> dump 0dsf 11200 1000 /dev/rwd0d /usr/src
> dump 0dsf 11200 1000 /dev/rwt0d /usr/src
> Thankfully, DOS was the first 100 Meg on my hard drive.
I've watched this, and the complaints about dump/restore...and my
own problems with dump/restore (I've been okay lately but I have had
restore refuse to read my NetBSD dumps before...and inter machine is
dicey)...and I've decided to switch back to tar for backups.
The GNU tar solves the device and special file problem...the various
time options can give you easy incremental backups...the tapes are
portable...and the format stays the same (only actual scsi/tape
problems bite you).
The advantages of dump/restore that I can see are...:
Easy incremental backups.
These are semi-bulletproof too...but need a quiet system
to really be bullet proof. A shell script around tar could even
drive tar using /etc/dumpdates...just update with the start time of the
tar...you might backup a file twice...but you definitely wouldn't miss
Sparse files backup sparsely
Nice, but not as much of an issue (almost not an issue) if you compress/gzip.
(I already do a dump | gzip | dd for some fs's).
Inode only changes get backed up (like mode changes)
Doable with gtar...or at least with gtar and find
dump does perform better than tar. Restore performs better than tar
but only for larger restores...single file restores take longer because of
dir read overhead.
Also...on my machine I can get tar to stream as well as dump..so the speed
difference isn't huge
Advantages of tar (other than those above):
Exclude/include files and other filtering
You can be picky about what to back up (nice to not bother with all those
.o's out of /usr/obj...or other stuff easily recreated if you are getting
tight on a tape.
Just kind of babbling...I'm still using dump admittedly, but only because
I have a pretty complete set of bacukp/restore scripts I developed using
dump. Once I've got those converted to tar...I switch. What would be
cool is a dump/restore like wrapper for tar to make it easy (and do things
like /etc/dumpdates handling...using that to drive tar with the right
time options, etc).
Mark P. Gooderum USSnail: Good Creations
Senior Consultant - Operating Systems Group 3029 Blackstone Ave. So.
"Working hard to be hardly working..." St. Louis Park, MN 55416
EMail: mark@Good.com Voice: (612) 922-3059
Interactive: mark@nirvana.Good.com Fax: (612) 922-2676