Re: [9fans] 9P vs. FUSE

["Eric Van Hensbergen" <ericvh@gmail.com>]

On 8/10/07, Enrico Weigelt <weigelt@metux.de> wrote:
> * Skip Tavakkolian <9nut@9netics.com> wrote:
> > > did anyone do any comparisons on 9P vs. FUSE for (mostly-)local uses ?
> >
> > fuse is a clever hack for doing user space fs in unix.
> > look at russ' 9pfuse in p9p.
>
> Okay, that's an FUSE-based 9p client.
> What about FUSE-based 9p servers ?
>

I don't think FUSE-based 9p servers makes any sense.  Over
simplifying, FUSE provides a user space API into the UNIX VFS layer --
9p provides an API and Protocol into Plan 9's file server interface
(which may be local kernel, local user, or across the network).

Plan 9's file server interface is an elegant (and small) approach,
UNIX VFS is a much larger, more complicated (and many would argue more
complicated and larger than necessary) interface.  Plan 9's interface
is well suited to Plan 9.  UNIX's interface is well suited to UNIX.

Now, that being said, we have 9p under UNIX (both in p9p and v9fs, and
many other incantations), and it seems to work just fine for many
things.  We took a stab at extending 9p to match some of the UNIX
semantics (links, special files, etc.) and it was called 9p2000.u and
is implemented in the v9fs client and the spfs server code (there is
an RFC if you google for it).

However, it was decided at the last IWP9 that we had probably taken
the wrong approach with 9p2000.u and it would probably have been
better to extend 9p with new operations that had different
syntax/semantics from standard 9p as these would be easier to filter
out.  I'm currently playing with a new design in my copious spare
time.

It was further suggested by some that a better approach on Linux/UNIX
would have been to take what we know from 9p and design a protocol
specific to the VFS (similar to FUSE but capable of transparent
network, etc.)

Some of the recent v9fs effort has been looking at 9p for
paravirtualized file system access between hosts using shared memory
transports.   Much initial work has been done using 9p and 9p2000.u,
but requests for more comprehensive solutions have been requested by
customers/interested-parties with full support for Linux capabilities.
 As such, there may be a foray into providing something along the
lines of a new set of extensions supporting all Linux VFS operations
(perhaps I'll call it 9p2000.l)

However, such support is mainly necessary for folks looking to remote
access feature rich on-disk file-systems.  I believe straight 9p is
more than adequate for 99% of synthetic file systems with something as
simple as 9p2000.u giving you extra bits necessary for basic UNIX
compatibility.

               -eric