Re: [PATCH v11 00/20] nfs/nfsd: add support for localio

NeilBrown
2024-07-08T04:10:45Z

On Sun, 07 Jul 2024, Chuck Lever III wrote:
>
> Both the Linux NFS client and server implement RFC 8154
> well enough that this could be an alternative or even a
> better solution than LOCALIO. The server stores an XFS
> file system on the devices, and hands out layouts with
> the device ID and LBAs of the extents where file content
> is located.
>
> The fly in this ointment is the need for NFSv3 support.

Another fly in this ointment is that only XFS currently implements that
.map_blocks export_operation, so only it could be used as a server-side
filesystem.

Maybe that would not be a barrier to Mike, but it does make it a lot
less interesting to me (not that I have a particular use case in mind,
but I just find "local bypass for NFSv4.1+ on XFS" less interesting than
"local bypass for NFS on Linux").

But my interest isn't a requirement of course.

>
> In an earlier email Mike mentioned that Hammerspace isn't
> interested in providing a centrally managed directory of
> block devices that could be utilized by the MDS to simply
> inform the client of local devices. I don't think that's
> the only possible solution for discovering the locality of
> storage devices.

Could you sketch out an alternate solution so that it can be assessed
objectively?

Thanks,
NeilBrown