Hello everyone!
I have an issue that I can't figure out and I'm hoping someone can get a new idea or set of eyes on this problem. I'm going to try and be as detailed as possible... but please ask any questions if I left anything out.
Basically I'm having an issue where i'm not getting the full 10gb transfers (or even close) when doing a Hyper-v move between hosts using 10gb nics. I get 2.5gbps if i'm lucky. These servers are not in production yet and are just being used to test a setup before being rolled out.
I have two similar but not identical Dell Poweredge R910 servers.
The two hosts have 2012 R2 Datacenter with only the Hyper-V Role installed. All updates, firmware and manufactures drivers applied, down to the bios, nics and raid cards as well.
I have installed one Intel X540-T1 10gbe card in each server in a x8 slot. I have these two cards connected via a straight RJ45 Cat6 patch cable (no switch, no crossover). The cable is 3ft long. I have hyper-v setup to use this as a live migration network by adding the nics ip's in each host under live migrations.
Storage is local between each server a mix of 10K Raid10 and Enterprise class SSD disks. When doing disk to disk (same server) transfers of large file I see up to 900MBps on SSD's so i don't think the storage is a bottleneck.
When I do a live migration move between hosts I get between 2-2.5gbps transfer speeds using this link.
I ran iperf between the two servers and consistently get between 6-6.5gbps so I know these cards are at least working close to their rated speed. I would have thought these tests should be closer to 10gbps though.
Not sure how to troubleshoot this. I have changed the nic setting to enable/disable VMQ, I have enabled/disabled jumbo packets as well as a bunch of other nic settings in an attempt to narrow this down. Nothing really seems to speed this connection up. I have also disabled the c states and c1e in the bios and set everything to maximum performance with no change in speed.
I have tried 3 different patch cables including a non supported 5e patch cable (just to see if the speed degraded) and the speeds stayed the same.
Any help or suggestions would be greatly appreciated.
Thanks!