Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!cornell!uw-beaver!rice!sun-spots-request
From: bzs@encore.com (Barry Shein)
Newsgroups: comp.sys.sun
Subject: Re: dd dumps?  fast restores?
Message-ID: <4423@xenna.Encore.COM>
Date: 30 Dec 88 01:36:32 GMT
References: <8811252107.AA05311@uf.msc.umn.edu>
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Original-Date: 17 Dec 88 19:39:39 GMT
X-Sun-Spots-Digest: Volume 7, Issue 78, message 4 of 10

A problem you would run into with using dd for full dumps and some sort of
find/tar command for incrementals is that you won't backup deletions.

This means that if a file is deleted between the full and the tar
incremental there will be no real record of that. This poses three
problems:

1. If, as you say, you tend to run nearly full partitions then when you
restore the incremental tar tapes you may run out of disk space and not be
able to complete the restoral. VERY annoying and time-consuming to work
around!

2. The reappearance of deleted files could be considered a security
problem (for example, Joe Prof deletes some sensitive files before going
away for a while because he wants to let someone use his acct while away,
or knows eventually his amazing grad students will find a way into
everything he leaves around only to discover on returning the files were
put back onto his account the day after he left and copies now hang on the
bathroom walls.)

3. Similarly, users get *very* confused when deleted versions of files
re-appear and you'll waste the time saved responding to frantic (although
usually not totally justified) mail.

See, I went thru this on a 3B5 in another life where we were forced to use
this type of backup scheme due to the non-existence of a backup utility
under SYSV. Ugh, think it through (note you probably could cobble
something together which restores deletions, I think we eventually did by
putting directory listings of changed dirs onto the tar tape and running
something over them on a restore to delete any files which needed
deletion, or at least we talked about it, it's been a while.) Then again
by the time you're finished you'd probably be only slightly ahead of using
dump/restore.

	-Barry Shein, ||Encore||