We have recently been trying to implement a Server 2012 instance of DFS across 2 of our main sites. The servers are Dell R720xd with Intel NICs installed with all the latest firmware drivers and updates installed. When the machines were on the same site, transfer speeds where 100-105MB/s transferring between them, however as soon as one was transferred to another site, these speeds have become 1-2MB/s. The link between the offices is a dedicated 100MB link with a single hop between our 2 main sites; ping response between the 2 sites is between 26ms (empty office) to 35ms (both offices at peak times). Our other site in London has a ping response of 20-21ms to our Liverpool site and doesn't experience these issues at all; achieving around 9.5MB/s transfer during peak times (it will hit almost 11MB/s when offices are quiet).
We have had our ISP investigate the link between our Manchester and Liverpool sites and can't find anything wrong at all; when we try and transfer a file from our old Netapp appliance (FAS2020) to the other site we achieve a much quicker 6-8MB/s (although it starts at around 2-3MB and climbs slowly).
We tried the various tweaks and policy changes on 2012 (disabling autotuning, rss, tcp chimney offload, bandwidth throttling, SMB signing etc) but to no avail. So we downgraded one of the servers to 2008 R2 and performed the same steps - unfortunately we still experience the same problems!
I am rapidly running out of ideas here - I thought the bandwidth throttling reg fix would sort our issues, but it appears not; although I had my suspicions that a 30ms ping time would not be classified as high latency enough to throttle back bandwidth.
Can anyone help??