Roch - PAE wrote:
Not possible. Nothing related to ZFS here and if NFS had
ways to make this better i think it would have been done in v4.
If we extended the protocol to allow for exclusive mounts
(single client access) then, I would think that the extra
knowledge could be used to gain speed... I don't know if
this was considered by the NFS forum.
This sounds very similar to delegations, quoting from RFC 3530
1.4.6. Client Caching and Delegation
...
The major addition to NFS version 4 in the area of caching is the
ability of the server to delegate certain responsibilities to the
client. When the server grants a delegation for a file to a client,
the client is guaranteed certain semantics with respect to the
sharing of that file with other clients. At OPEN, the server may
provide the client either a read or write delegation for the file.
If the client is granted a read delegation, it is assured that no
other client has the ability to write to the file for the duration of
the delegation. If the client is granted a write delegation, the
client is assured that no other client has read or write access to
the file.
However IIRC the current state of the NFSv4 client in OpenSolaris is
that this functionality is not supported. My knowledge of what we have
done in NFSv4 in OpenSolaris is a little rusty though so I highly
recommend follow up with the NFS community.
As for NFS performance it isn't all bad it is just as you have pointed
out that there is a pathological case that is being used in these tests.
For some idea of what NFS can do see:
http://blogs.sun.com/shepler/entry/spec_sfs_over_the_years
--
Darren J Moffat
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