[Beowulf] mixing of Infiniband HCAs in cluster

[Mikhail Kuzminsky]

We have a pair of IB 4x (Mellanox MTLP23108) HCAs used currently for 
direct switchless connection of pair of nodes.

Now we plan to buy 8-port (MTK37900) or 24-port IB switch w/HCAs, 
which may be also DDR IB. And we want to build this cluster including 
also old pair of nodes w/MTLP23108 HCAs. But is this possible - to 
have both HCA kinds (DDR and usual IB 4x HCAs) connected to the same 
switch ? If the answer is "yes", is it necessary to setup all the 
DDR-HCA drivers manually for work w/"4x speed" or all the necessary 
things will be done via negotiations ?

Yours
Mikhail Kuzminsky
Computer Assistance to Chemical Research Center,
Zelinsky Institute of Organic Chemistry
Moscow