Re: Alternate solutions (Was: Re: NFS still has caching problem)

Larry McVoy (lm@neteng.engr.sgi.com)
27 Jul 1996 18:34:08 GMT

: Why not base the new file-system on NFS? Incremental changes are more
: likely to be accepted than total re-implementation (not that I should
: say that, considering X++ ;-)) and it eases upgrade.

It's easy to extend, transparently, any RPC based service. If you look at
them, they are a list of procedure calls with integer identifiers.

The original intent (long since lost) of the RPC versioning system was that
you would start off with version one, which had some number of interfaces.
You relized that you had a bug in one interface, so you revved the version
number, fixed that one procedure call, and left all the other stuff. Or
you realized that you had forgotten one interface (ACLs come to mind) and
you add a procedure to the end of your list (IBM has done this for ACLs for
AIX).

NFS v3 certainly did not take this approach, it's so different it might as
well be some other name.

Linux could (carefully) add a few procedure calls to do what you need to
the end of the v2 list and all would be well. You could check, out of
band at mount time, if the other side supported your new stuff, and use it
only when it works - I've done this for SunOS for POSIX and in IRIX for
BDS support.

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Larry McVoy     lm@sgi.com     http://reality.sgi.com/lm     (415) 933-1804