NFS Problems under Redhat 6.0

[Terry Barnaby]

> On Tue, 15 Jun 1999, Terry Barnaby wrote:
> > We had problems with NFS in 2.2.3 -> 2.2.6 kernels. The main one being
> > some problem with caching. If on one machine you deleted an executable
> > another machine with the file system NFS mounted could still execute this
> > executable ! The change would only happen latter.
> 
> AFAIK, it is normal in NFS that such changes appear later on the other
> machines. The questions is just: How much later does this happen?

With the machines in time sync, it is around 1 min. This never happened
using kernels up to 2.0.36. It is seen when ruuning a make on one machine
and running the executable on another. The new execuatable will not be
run for around a minite.
 
> 
> > Also large files of the form .nfs* started apearing in server directories.
> 
> I'm not quite sure on this, but it might happen if you delete a file
> which is still in use by some process. So the file can not just be
> deleted, but it's renamed to be deleted later.
> (On a local filesystem a file to be deleted which is still in use by
> another process is only removed from the directory, but the blocks are
> still there. Only when the last process closes that file, then its
> blocks are freed. As NFS is not block oriented, another approach is
> required).

This is probably from the make being run while the execuatble in in execution
on another machine then and would account for the behaviour seen. I would have
thought that the NFS would at least do a remote check to see if the file
has changed prior to using its cached copy ?

> 
> Please correct me if this is wrong.

I think you are right in that this is the way it appears to work now. But is
this correct for NFS ?

> 
> - Felix
> -- 
> Felix Rauch                      | Email: rauch@inf.ethz.ch
> Institute for Computer Systems   | Homepage: http://www.cs.inf.ethz.ch/~rauch/
> ETH Zentrum / RZ H15             | Phone: ++41 1 632 7489
> CH - 8092 Zuerich / Switzerland  | Fax:   ++41 1 632 1307
> 

-- 
  Dr Terry Barnaby                     BEAM Ltd
  Phone: +44 1454 324512               Northavon Business Center, Dean Rd
  Fax:   +44 1454 313172               Yate, Bristol, BS17 5NH, UK
  Email: terry@beam.demon.co.uk        Web: www.beam.demon.co.uk
  BEAM for: Visually Impaired X-Terminals, Parallel Processing, Software Dev
                         "Tandems are twice the fun !"