Parallel distributed ...cables lenght

donminoti · March 12, 2017, 15:18

Hi
Please, I am setting up a small cluster with 4 nodes ( 8 CPU , 64 cores), plus a master node (8 cores). I want to make head node participate to computation. To avoid batch & scripts and to launch solver from graphical interface.
Is it a good idea ?
Another point, is the cable lengths. The 4 nodes are linked to the switch through 2 meters cables, these nodes and switch are in separated room (lound), however the master (in my office) would be connected to that switch by a 15 meters cable!,
Could this difference in cable lengths creates a latency during solution process ?
The connection is 10GbE sfp+..
Thank you
BR

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-Maxim- · March 14, 2017, 03:20

I don't have any experience in setting such a thing up and I haven't used sfp+ yet but from what I've heard, those computers should be connected with an infiniband. That might be old knowledge since your 10Gbs sfp+ sounds like quite a data throughput...

evcelica · March 14, 2017, 15:21

I have seen slight latency increase in my 50meter infiniband cable. The other 1 meter and up to 20 meter cables all perform identically as far as I can tell. I just have the one node that is slightly slower.

March 12, 2017, 15:18	Parallel distributed ...cables lenght	#1
donminoti Member belamou Join Date: Apr 2009 Posts: 40 Rep Power: 18	Hi Please, I am setting up a small cluster with 4 nodes ( 8 CPU , 64 cores), plus a master node (8 cores). I want to make head node participate to computation. To avoid batch & scripts and to launch solver from graphical interface. Is it a good idea ? Another point, is the cable lengths. The 4 nodes are linked to the switch through 2 meters cables, these nodes and switch are in separated room (lound), however the master (in my office) would be connected to that switch by a 15 meters cable!, Could this difference in cable lengths creates a latency during solution process ? The connection is 10GbE sfp+.. Thank you BR Sent from my SM-G360F using CFD Online Forum mobile app

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March 14, 2017, 03:20		#2
-Maxim- Senior Member Maxim Join Date: Aug 2015 Location: Germany Posts: 413 Rep Power: 14	I don't have any experience in setting such a thing up and I haven't used sfp+ yet but from what I've heard, those computers should be connected with an infiniband. That might be old knowledge since your 10Gbs sfp+ sounds like quite a data throughput...

March 14, 2017, 15:21		#3
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,196 Rep Power: 24	I have seen slight latency increase in my 50meter infiniband cable. The other 1 meter and up to 20 meter cables all perform identically as far as I can tell. I just have the one node that is slightly slower.