[Beowulf] "dual" Quad solution from Tyan

[Andrew Piskorski]

On Mon, Feb 27, 2006 at 08:49:23PM +0000, Ricardo Reis wrote:

> The target machine I was looking for was 8 node with 
> dual processor Opteron (16 CPU). The machine that was at the presentation 
> is
> 
> http://www.cybernex.co.uk/tyan_vx50_quad_opteron_servers.htm
> 
> which means 8 CPU, dual core. And all are connect with hypertransport 
> which meand I got ready of latency I figure. So...

> The professor head of the lab wants me to know "if that is so good why 
> isn't everyone buying one?"

Where is the data suggesting that it's "so good"?  And what do you
want to use it for?

> From: Joe Landman <landman at scalableinformatics.com>
> See page 2 of ftp://ftp.tyan.com/datasheets/d_s4881_104.pdf

Ah.  Apparently that box uses a Tyan S4881 4-socket motherboard which
with a special M4881 add-on riser card, can be extended to 8 sockets.
There are other 8-socket Opteron motherboards out there - Iwill makes
one, there are probalby others as well.

So you seem to want to compare a single big 8-socket ccNUMA Opteron
box to a cluster of four 2-socket boxes.

On a per-cpu or per-motherboard basis, the 8xx series Opterons and
4/8-way motherboards are going to be SUBSTANTIALLY more expensive than
2xx Opterons and 2-socket motherboards.  How do the costs compare on
an aggregate "per 8 sockets" basis?  I don't know, get the prices and
add them up.

Do you NEED shared memory?  Then the 8-way box (or SCI?) is probably
the only way to go.

Do you NEED low latency?  The 8-way box PROBABLY has better latency,
but perhaps Infinipath HTX adapters between 2-socket nodes would give
similar (or possibly better in some cases?)  latency - you need to
compare actual performance numbers.

Note that that Tyan 8-socket box does not have any extra HTX slots, so
you if you wanted to cluster multiple such boxes you would have to do
so over its PCI Express slots or built in Gigabit Ethernet.

-- 
Andrew Piskorski <atp at piskorski.com>
http://www.piskorski.com/