NFS on NFS?

[Rick Macklem]

On Tue, 17 Jul 2007, Eric Anderson wrote:

> Here's what I'd like to do:
>
> - Mount NFS export from filer 'A'
> - Export that mountpoint to clients via NFS
>
> I've already tried it, and it doesn't quite work.  FreeBSD allows me to 
> export it (doing tricks like null mounting the NFS mounted directory on a 
> different directory, etc).  But when a client mounts it, it has issues.
>
> Does anyone know if this is a reasonable problem to solve for FreeBSD, or is 
> it so much work that it isn't worth it?
>
> Oh, and please - I understand the implications of doing such a thing, no 
> worries, I still want to.
>
Since this wasn't allowed for NFSv2 and 3 (due to issues such as
providing a T stable file handle), clients probably won't handle
it well. In general, NFSv2 and 3 clients will get really confused
when the fsid or fid changes and break in subtle ways if the file
handle is not T stable (refers to that file only, including long
after the file is deleted).

NFSv4 does allow mount point crossings (fsid to change), but some
clients, such as Solaris10 are confused by it.

An easier solution might be to write a simple proxy that just forwards
the RPC requests/replies to the actual server.

rick