40Gb Active fibre

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Falloutboy

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Oct 23, 2011
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Possibly a stupid question but would a 40gbit active fibre cable from Mellanox work on a 56gbit host adapter at 40gb speed? or will that just not happen.
 

i386

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Mar 18, 2016
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I tried a QSFP28 (100GBE) AOC cable with a 40GBE switch (Arista 7050q) and 100GBE mellanox nic.
Got a 10GBE link :/

So my answer is "It depends" :D

Do you want to connect two hosts directly?
With a switch?
 

Falloutboy

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Oct 23, 2011
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I tried a QSFP28 (100GBE) AOC cable with a 40GBE switch (Arista 7050q) and 100GBE mellanox nic.
Got a 10GBE link :/

So my answer is "It depends" :D

Do you want to connect two hosts directly?
With a switch?
Direct, It's all Mellanox I am actually looking for as later version as possible of Linux server software at the moment which will still support the ConnectX 2's I have so I can at least get a pair of server systems able to talk at 40Gb. then at least I have a starting point.

Then I will decide if I need to go any higher and purchase new cards, the major requirements for later models will be they must be PCIex8 Gen 2 or Gen3, obviously on my older server Gen3 won't make any difference but it would be nice if I could reuse the 40Gb Mellanox Active fiber I have as this would initially cut down costs a little in the beginning.

I have managed to run them in Eth mode in windows and once I have things confirmed as up and running will look at upgrading my Windows 10 Pro PC's to Windows Pro Workstation, under the proviso they can store files and I can max out these connections. So far the best I have managed is a bit over 400Meg/s one way or 200Meg/s bidirectional which is not the sort of speed I was looking for especially when they should be able to operate much faster, but my understanding is that is only in Server/Workstation environments. I am hoping that it extends to a Windows 10 Workstation OS talking to a Linux Server OS.

Please excuse any spelling problems, I have gotten better over the years but I am dyslexic and everything I just typed is now a bit of a blur otherwise I'd correct it.

Actually I find it a bit amusing, Mellanox/nvidia want you to buy the latest gear which costs a fortune but without being able to get a basic setup done and working the way I want I absolutely will not sped that kind of money, so they are in effect by not supporting this stuff so that people can prove things work stiffling their own sales.
 
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i386

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Mar 18, 2016
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So far the best I have managed is a bit over 400Meg/s one way or 200Meg/s bidirectional which is not the sort of speed I was looking for
Did you measure your local disk performance before looking at the network stack?
 

BeTeP

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Mar 23, 2019
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I tried a QSFP28 (100GBE) AOC cable with a 40GBE switch (Arista 7050q) and 100GBE mellanox nic.
Got a 10GBE link :/

So my answer is "It depends" :D
This situation is completely different from OP's. In his case there is no uncertainty. All FDR14 adapters support FDR10 as well.
 

i386

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Mar 18, 2016
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The adapters yes, the active optical cable(s)?
No, at least not the mellanox qsgf28 ones that I have :D

Edit: I think I didn't read the op properly :p
 

Falloutboy

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Oct 23, 2011
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Did you measure your local disk performance before looking at the network stack?
Admittedly no, realized that probably the best test would be from ram disk to ram disk, or possibly iperf v2 not windows to windows file copy. I have just been experementing with ubuntu and got the pair of cx2's up in infiniband, according to iperf it's doing 20 gig on a 40 gig link