[Beowulf] Mare Nostrum (not quite COTS)

Patrick Geoffray patrick at myri.com
Sun Feb 20 23:46:59 PST 2005

Hi Vincent,

Vincent Diepeveen wrote:
> Which myrinet cards are in Mare Nostrum?

Single link PCI-X D cards, with 4 MB of SRAM to be comfortable with 
multiples routes between a lot of nodes. The NICs for the BladeCenter 
have a specific format: smaller than regular half-size PCI boards, NIC 
is // to the mainboard and has no fiber transceiver (goes to the OPM via 
the Bladecenter backplane). Available only via IBM.

> What one way pingpong latency can it get from 1 end of the machine to the
> other end of the machine?

I don't know, I didn't work on this machine. It would depend on the 
number of crossbars and lengths of fiber. I uses the new switches with 
32-port crossbars, so the max path should not be longer than 7 hops if 
my memory is right. At one time, the PCI-X on the JS-20 blades was 
clocked at 100 MHz, I don't know if it has been bumped to 133 MHz since.


Patrick Geoffray
Myricom, Inc.

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