Which 10GB DAC for low power?

[hebeldebel]

Hi everyone,

I am setting up my new server and I have a Aruba Instant On 1930 24G (JL683A) switch with 10GB SFP+ ports.
Reading through articles and blog posts on the internet I came to the conclusion that the most energy efficient solution would be to use a DAC connection.
Do you agree with that?
If so, what kind of DAC and PCIe adapter would you buy to use in a 2U server rack (half height) together with this switch?
Are there some "cheap" solutions with very little power draw? I read that 1W could be possible, is that right?

kind regards,
hebeldebel

 

[mach3.2]

DACs are basically 2 pairs of coaxial cables.

What OS are you running? Intel X520 and Mellanox ConnectX-3s are plentiful on ebay and can be bought for cheap. DACs are also pretty cheap on ebay.

For ESXi8, you'd want to avoid the ConnectX-3 cards because there are no drivers for it. ConnectX-4 and up cards for ESXi8.

I have the same Aruba switch, unsupported tranceivers/DACs will work just fine, but the switch indicator lights will blink orange.

 

[hebeldebel]

Thank you for your reply and the link.
I am running debian 12 on my server.
Do you happen to know how high the power draw of these adapters in your system is?

based on your response, I think I would probably go with this offer:

Mellanox ConnectX-3 PCIe x4 NIC 10 Gigabit 10GBe SFP+ CX311A Server Adapter LP

Mellanox ConnectX-3 PCIe x4 NIC 10 Gigabit 10GBe SFP+ Single Port Server Adapter CX311A LP Die professionelle Mellanox ConnectX-3 10Gbit Single Port 10 GB Netzwerkkarte MCX311A-XCAT für den PCIe x4 3.0 Anschluss ist mit...

www.its-haehnlein.com

and

Cisco 3m SFP+ DAC Kabel 10GB 10 Gigabit Twinax Twinaxial Cable SFP-H10GB-CU3M

Cisco 3m SFP+ SFP Kabel 10GB 10 Gigabit Twinax Twinaxial Cable SFP-H10GB-CU3M - SFP+ auf SFP+ zB für 10G Netzwerkkarten / Switches / etc. - bis zu 10G Geschwindigkeit - Kabellänge: 3m

www.its-haehnlein.com

Does this look like a good combination? Is the price at least somewhat ok?

 

[mach3.2]

The ConnectX-3 cards shouldn't draw more than 10W if I'm not wrong. However it does prevent your processor from going into C3 state, so if your server is idling most of the time, you'd expect to see higher idle power consumption. I have no experience with Intel X520 cards.

Cross compare the prices on ebay, but I'd have to say the ConnectX-3 does look a little pricey (like 2x of what you can find on ebay)....

 

[hebeldebel]

Thank you very much for the input, C3 state is definitely a thing I had not considered.
My setup currently uses 18W idle and an additional 10W would really make a difference (don't want to get into a "electricity is cheap" discussion, though)

 

[nexox]

I have a Solarflare 7120 dual sfp+ card in my latest build, it seems to run cooler than my single port X520s and my CPU (Xeon E5 v2) has no problem dropping all the way down to C6 most of the time. Linux support is great, not sure about other platforms.

 

[hebeldebel]

thank you for the advice about the Solarflare, I will look into it.

I think I missed this thread:
https://forums.servethehome.com/index.php?threads/best-low-power-sfp-cards.25824/

where the SFN7xx2F is mentioned with 5.9W, my bad.

It also mentions the "TEG-10GECSFP v2.0R", which I tried to look up on the internet, but there are not many test or blog posts to be found. It is also hard to find as a used card.