[pnfs] MDS exporting pNFS and non-pNFS file systems

[Tom Tucker]

Dan:

I'm currently working on a pNFS pseudo file system prototype that allows
you to specify file layout policy for any file system that is exportable
via NFS. This pseudo filesystem acts kind of like a super-block proxy
that allows you to plug in file layout policy and pNFS policy for a
filesystem based on mount point instead of on file system type.

Perhaps this kind of idea is suitable for your purposes? In other words,
since the exports ops are per-fs, if you want to modify them for a given
fs, you need an abstraction layer. 

Tom

On Tue, 2008-02-05 at 16:09 -0800, Muntz, Daniel wrote:
> What are people doing to support exporting pNFS and non-pNFS file
> systems from an MDS?  The information from EXCHANGE_ID is not
> per-file-system, so can't be used to determine if a particular file
> system is pNFS-enabled.  Based on talking with Ricardo and Mike, we were
> thinking perhaps GETATTR could be used.  E.g., GETATTR could return a
> layout type of 0 for entities that do not support pNFS.
> 
> Perhaps the IBMers have some thoughts on this.  If you had a server
> exporting 2 GPFS file systems, and you wanted to export one with pNFS
> and one without, how would you want to handle this in the protocol?  For
> that matter, how would you want to handle it from a UI perspective?  For
> GPFS, an /etc/exports flag might make sense.  This wouldn't really work
> well for spNFS though.  For GPFS I assume you could switch back and
> forth between exporting with/without pNFS.  For spNFS, you're committed
> to exporting with pNFS (exporting without pNFS would result in access to
> the files on the MDS).
> 
>   -Dan
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