Re: Configuring flex file DS on Linux upstream

[Tom Haynes <loghyr@excfb.com>]

On Thu, May 26, 2016 at 02:41:18PM -0400, J. Bruce Fields wrote:
> On Thu, May 26, 2016 at 11:31:34AM -0700, Tom Haynes wrote:
> > fwiw, I'm looking at being able to specify a remote DS for the next version
> > of the flex file server. Is it worth considering that in the discussion
> > being done in Andy's thread about "Configuring fs_locations on Linux upstream server pseudo fs for session trunking"?
> > 
> > For example:
> > 
> > /mds *(rw,pnfs,ff_ds=192.168.2.101.2049:/ds,insecure,no_root_squash,no_all_squash)
> > 
> > And in the far future, I'd want it to be a multipath list.
> > 
> > I don't see this as something that changes often and the exports
> > seem like the most natural fit.
> 
> I don't understand the ":/ds" part.  You just look up stuff by
> filehandle on the data server, so we shouldn't have to know anything
> about paths there, should we?  Or is the problem that it might need to
> mount something first in the v3 case?

You need at least the root fh in order to create/remove files:

 struct CREATE3args {
           diropargs3   where;
           createhow3   how;
 };

 struct REMOVE3args {
           diropargs3  object;
 };


> 
> Otherwise, I guess exports makes sense, as long as this really is
> per-export information.
> 
> The thing that's a little different about the multipath information is
> that that's really a global server property, not something that can vary
> from one filesystem to another.

Thanks for the explanation...