From mboxrd@z Thu Jan  1 00:00:00 1970
Message-Id: <200008011306.JAA16082@cse.psu.edu>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] Installing the updates
From: "rob pike" <rob@plan9.bell-labs.com>
Date: Tue,  1 Aug 2000 09:06:08 -0400
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	A user could have the distribution source on a CDROM and view it via a
	cache file
	server. This would store only the files that have changed - using copy
	on write.
	I suspose this could be extended to storing only the blocks that have
	changed, or
	even file diff(1) output, or wrap(8) file even...
	
	I'am not sure if this is interesting or hedious :-)

This is the essence of what BSD calls union directories.

-rob