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Backup to file server
Date: Wed, 4 Mar 1992 15:54 EST
From: barmar@Think.COM (Barry Margolin)
Does anyone have any modifications to the LMFS backup software that
allow it to use files on a file server as the backup medium instead of
tapes. I've been using the Unix RTAPE server to dump to 9-track
reel-to-reel tapes on a Unix server, but we're phasing out those drives
here; most of our Unix dumps are done on Exabytes. Also, the amount of
data that changes on our LMFS server is little enough that it's hard to
justify wasting a whole tape; I just did a three-month consolidated
backup, and only dumped 28 files.
I would like to know this too -- would be much preferable to the solution below.
I already asked Symbolics, and they don't have anything that does this.
They suggested that I mount the LMFS as an NFS server and use tar. But
that will lose version numbers (although I think there's a variable that
can be set to make all version numbers show up) and some file
properties. Also, Unix (or at least SunOS) clients really don't like
slow NFS servers; they can bog down the entire machine, and I don't want
to screw the Unix users while I'm dumping.
This is what we do. DAT unit on Sun, mount Symbolics NFS, backup. The
variable you want to set is
(setq nfs:*newest-versions-of-files-appear-to-unix-without-version* nil)
before the backup obviously. I believe there are similarly-named
variables for different kinds of hosts. Note that you must do this even
if you don't care about version numbers: it can happen that your newest
version (which would otherwise appear without a version number at all)
will be wiped out by an older version on restoration: restored version
that has no number is given the number 1, if your actual version 1 was
put onto the tape after the newest version, it will overwrite your
(Soapbox: Now that Unix file system is basically becoming the standard,
why don't they incorporate version numbers into it?)
I was disappointed to find recently that owner/time-date information is
lost on restoration (though at least the latter is there on the tape).
I believe if you are using NIS (formerly yellow pages) you will get the
owner info back; we're not using it so files are put on tape with
Unix "nobody" as the owner. If you run NIS, you should get proper owner,
and I think also time-date info. Other file properties are probably lost
as tar/Unix has no way of knowing about them (links are saved as Unix soft
As for bogging down I don't know. I run the backup at 1 A.M. but no one
uses our Sun anyway -- it's just a slave for the Symbolics. The backup
does bog down the Symbolics file server (we have a 3650, with an XL
I'm sure it's much better).
Liam M. Healy
Code 8242, Naval Research Laboratory, Washington, DC 20375