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

From: David Howells (dhowells@cambridge.redhat.com)
Date: Mon Oct 07 2002 - 10:36:17 EST


> 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
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