question on SunOS 4.1 TFS...

[Chuck Musciano]

Larry McVoy (lm at sun.com) writes:
> You've misunderstood TFS (Translucent File System).  It's a stacked file
> system - it sits on top of another file system and requests for files are
> satisfied from the top file system if the files exist in that system and
> from the bottom file system otherwise.  The example is an obviuos use: if
> a use has some program (that is broken because: ) that insists on living
> in /usr/local/bin (like mh) and you can't write in /usr/local/bin (like
> me) then you can put your program in an otherwise empty file system and
> mount that file system over /usr/local/bin.

Ah, those who forget history are condemned to repeat it!  Older Sun users
will recognize Translucent File Systems to be a snappy new name for a very
old idea.  Go back, way back, to 1964, and IBM's OS/360.  People who know
the difference between an 026 and an 029 keypunch might recognize

	//SYSIN    DD   HOSAJM.FIRST.DATASET
	//         DD   HOSAJM.NEXT.DATASET

as the way you created "translucent" file systems, concatenating multiple
datasets into one logical dataset.  A very handy concept, one missing from
Unix for a long time.  A new idea?  No way.  A good idea?  Yes.  I'm glad
it will be in 4.1.

Chuck Musciano				ARPA  : chuck at trantor.harris-atd.com
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