Re: [PATCH] AFS filesystem for Linux (2/2)

David Howells
2002-10-07T15:31:23Z

> NFSv4 does not specify that files need to be backed by local storage
> the way AFS does if that is what you mean. However it does offer
> AFS-like features (such as file delegation / leases) that make a
> cachefs a much more feasible proposition.
>
> I, for one, would be very interested in seeing a cachefs add-on for
> NFSv4. I think that it would be of great use for GRID / distributed
> computation applications, which is where my personal interest in NFSv4
> lies.

Can you give me some sort of idea as to what keys I might use for indexing?

For instance, AFS has the following:

PRIMARY KEY SIZE AUXILLIARY DATA IN INDEX
============== ============== ============================
cell name up to 64 ASCII - volume location database
server addresses

volume ID 32-bit number - name of volume
- associated keys
- fileserver addresses

vnode ID 32-bit number - access time
- vnode metadata record pointer
- vnode ID version
- vnode data version
- modify time
- size
- data block pointers

Each index entry of course has a pointer back up the hierarchy.

Furthermore, to determine whether a cached file's contents are still valid, I
can compare the the vnode ID version and vnode data version numbers against
the server.

Not all these indices and keys will necessarily be useful for NFS.

David