[rescue] IBM on ebay

[Francisco Javier Mesa-Martinez]

On Fri, 17 May 2002, Joshua D Boyd wrote:

> On Fri, May 17, 2002 at 01:46:05AM -0700, Francisco Javier Mesa-Martinez wrote:
> > On Fri, 17 May 2002, Sridhar the POWERful wrote:
> > 
> > > The only RS/6000's that have anything approaching "mainframe class"
> > > performance are SP's, which are essentially smaller RS/6000's with
> > > ancillary I/O processing and shared-memory clustering.  I want one. 8-)
> > 
> > As a poor fool that has had to spend many sleepless nights programming SP
> > system(s), I can tell you that the SP/2 is not a shared memory machine.
> > There is no single adress space, it is just a glorified cluster with each
> > node being an actual RS6K workstation, and some fancy switching topology
> > for internode communication. The only ime shared memory operation can be
> > achieved is inside an SMP node, all internode communication is performed
> > via message passing (usually using some sort o'MPI).
> 
> So, they couldn't even be bothered to do something along the lines of
> what Mosix did? (SSI over a network).

Nope, MOSIX doesn't do SSI over a network. It is a cluster scheduler, just
like condor. The SPs have something like Mosix... a cluster scheduler of
sorts, but in order to do inter-process communication you still need to do
message passing (this is also true for Mosix).

Both, Mosix and SP, do abstract the cluster for you. I.e. you only see the
front end node, and you submit jour jobs to it. A job can consist of
several processes, and the scheduler will try to assign them to unused
nodes, or migrate them as soon as resources are avaliable. But it does not
take care of the interprocess communication.

The only machines that provide SSI facilities over cluster are still NUMA
machines (ala SGI Origin, HP Superdome, IBM/Sequent....)
  
> > Why would anyone want one of these machines is beyond me... but it seems
> > that IBM was able to market them pretty well.... A large SGI system with
> > ccNUMA, now THAT I do want!
> 
> I'll take anything, but vector machines occupy a special place in my dreams.

Clearly you have never have to program any of them! :-)