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From: fnf@riscokid.UUCP (Fred Fish)
Newsgroups: comp.sys.sgi
Subject: Re: Questions bru-ing in my mind
Message-ID: <14374@mcdphx.phx.mcd.mot.com>
Date: 10 Jan 91 14:38:59 GMT
References: <1990Dec21.174239.11753@odin.corp.sgi.com> <1990Dec24.155048.29640@cunixf.cc.columbia.edu> <1990Dec26.200730.7738@odin.corp.sgi.com> <1990Dec28.170722.18489@cunixf.cc.columbia.edu>
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Reply-To: fnf@riscokid.UUCP (Fred Fish)
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In article <1990Dec28.170722.18489@cunixf.cc.columbia.edu> shenkin@cunixf.cc.columbia.edu (Peter S. Shenkin) writes:
>I've been thinking about something that I first noticed several years ago
>when restoring a multi-user VAX from a 0-level (ie, full) dump tape plus
>several incrementals, following a disk crash.
>
>When you do such a restore, you get all the files that were there as of
>the time of the last incremental, but you also get files -- a whole lot of
>files, in my experience -- that users had deleted since the 0-level dump
>was made.  That is, you don't really restore the file system;  you get
>a lot of chaff in there along with all the wheat.  I personally found that
>weeding the extraneous stuff out was a real chore.  And where disk space is 
>tight, this process could actually overflow available storage.

The brumenus product from EST includes a facility called "snapshots", in
which a log is kept of all the files in a given tree.  Each backup has a
snapshot associated with it.  Given the snapshots, you can do diffs
between them to find out interesting things such as what files were
added between any two backups, what files were changed, and what files
were deleted.  So, you can use the "what files were deleted" info to
remove files that disappeared between two backups (say A and B), by
restoring A, deleting the appropriate files, and then restoring B.
It's relatively straight forward for a source customer to extract this
snapshot and "snapdiff" facility from the menus code and use them in
their own shell scripts.  Also in there is a "namefilter" which does
the inclusion/exclusion list sort of thing that everyone seems to want.

-Fred