Two 10g SFP+ cards in a PCIe 3.0 x 4 port—will both connect properly?
Two 10g SFP+ cards in a PCIe 3.0 x 4 port—will both connect properly?
Hey, you're building a budget 10G freenas setup. You have an old motherboard with just one PCIe 3.0 x16 port and one x4 slot (which is actually an x16 port). You're thinking about using the x16 for storage. It looks like the cheap 10G NICs you're seeing online are usually PCIe 2.0 x8 cards, especially if you're using Intel or Checosio as suggested for freenas. Single-port cards are pretty rare. It's a shame that Melanox chips don't work well together—they seem cheap for a reason.
Your questions: Would a 2 x 10G port card with a PCIe 2.0 x8 interface in a PCIe 3.0 x4 slot technically let you use one port at full speed? I assume it would run at PCIe 2.0 x4, which should cap at 16 Gb/s. But I'm not sure if that's straightforward.
Another thought—if you go for a PCIe 3.0 x8 card, can you expect one port to handle more than 10Gb/s? Does it really matter which slot you use since everything has to go through the x4 port? I guess you could just use the x4 slot for storage, but I know these are just theoretical limits and real-world performance won't be that high.
Thanks, and don't worry if this sounds a bit off.
I'm not familiar with the newest FreeNAS releases, but I can confirm the Mellanox ConnectX-2 MNPA19-XTR. From my experience, plug-and-play works well. You should be able to fully utilize it, though you might find it challenging to push both NICs to their limits at the same time. If you don't require constant maximum performance, it should function adequately for your needs.