Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!pacbell!hoptoad!gnu
From: gnu@hoptoad.uucp (John Gilmore)
Newsgroups: comp.sources.d
Subject: Re: Wiping out /bin in OS upgrades
Message-ID: <4293@hoptoad.uucp>
Date: 1 Apr 88 12:39:28 GMT
References: <1682@desint.UUCP> <1007@mcgill-vision.UUCP> <46626@sun.uucp> <2240@isis.UUCP>
Organization: Grasshopper Group in San Francisco
Lines: 35

I agree completely that OS upgrades should preserve locally-modified
state somewhere so that the administrator can reconcile it after the
upgrade.  Installing Sun releases is a major trauma -- I tend to
allocate about a week for it unless it's a minor (updates only) release.
It helps a *lot* to have some spare disk partitions (or spare disks) --
you can copy your old stuff onto the spare partitions before you install (and
make *damn* sure that you check the little nondefault box in Setup
that causes it to erase all your other disks -- I either power them down
or turn on the write protect switches, if they are separate disks).
Then you have both online at once and marvelous tools like "diff" can
come into play.

I think that a well thought out upgrade procedure could be:

* Back up the world on tape
* Read in some upgrade scripts from the new release tape
* Run these scripts, feeding them the OLD release tapes, so they can
diff them against the disks and produce lists of changed files (possibly
diffs, for the humans' perusal).
* Sysadmin gets a chance here to clean up his system and rerun the
scripts, if desired...s/he may not even know that all this stuff has
changed, and might want to investigate.  Also, cleaning up at this
stage makes for less to do later.
* Now run the install script, which saves the old files that weren't
straight off the release tape, then installs the new release tapes.
* Install script does whatever merging it knows about (e.g. mfr changed
the format of some file, it can convert the old one for you)
* It produces a report on disk including what it merged, and lists of
files that were changed in the old release and should be merged by hand
into the new release.  The install scripts should NOT just dump their
output on the screen, where it will disappear!
* Sysadmin runs the system as best they can straight off the new release
tapes, while merging in their changes by hand.
-- 
{pyramid,pacbell,amdahl,sun,ihnp4}!hoptoad!gnu			  gnu@toad.com
		"Watch me change my world..." -- Liquid Theatre