Bug#627655: linux-image-2.6.39-1-686-pae: missing NFS4.1 / pNFS support

[Paul Millar <paul.millar@desy.de>]

Hi Bastian,

On Monday 23 May 2011 12:17:00 Bastian Blank wrote:
> severity 627655 wishlist
> thanks
> 
> On Mon, May 23, 2011 at 10:35:57AM +0200, Paul Millar wrote:
> > Severity: important
> 
> Please specify, why this is appropriate.

Sure.

Some scientific communities require access to huge amounts of storage (in 
WLCG, the current largest sites are ~10 PB; there thousands of sites spread 
across the world).  Traditionally, this has been the high-energy partial 
physics community; however, increasingly, other communities are analysing more 
data than can fit on (or pass through) a single server.

Previous versions of NFS assumed the data was available from the same server 
as the filesystem metadata: there was a single NFS server that one mounts.  
This approach simply doesn't scale to the high-capacity / high-throughput 
needed by scientific analysis.

Therefore, until recently, the only scalable solution was linking against 
custom libraries that implement proprietary protocols.  These libraries 
provided the required throughput but are non-standard and tend to be tuned for 
specific storage software.  You can see one such library here:

	http://packages.debian.org/sid/libdcap1

there are several others.

Providing custom libraries has worked for scientific communities that use 
custom analysis software.  Such user-communities have the flexibility to link 
their software against a custom library and access their data through the 
POSIX-like layer provided by the custom library.

Increasingly, new scientific communities are using software that they either 
don't want to, or can't, modify.  This means that they cannot use the existing 
solution of linking against a custom library; instead, their IO must go 
through the standard filesystem.

With the provision of NFS v4.1 / pNFS, the Linux kernel allows site-admins to 
mount these large storage systems.  This allows user-communities access to 
large storage with normal POSIX IO and without using any custom library.

Without out NFS v4.1 / pNFS, some users are simply unable to take advantage of 
the large storage facilities that already exist.

Without support for NFS v4.1 / pNFS in a Debian kernel, sites offering large 
storage for their users are forced to hand-compile their kernels, with the 
options enabled.

I believe this is a "major effect on the usability of a package, without 
rendering it completely unusable to everyone."

> > Current Debain Linux kernels are build with neither option enabled (the
> > PNFS one is even missing from the config file).
> 
> Noone requested it yet.

OK, I'm the first then :-)

Cheers,

Paul.