We just put our first Hyper-V based web solution online about a month ago (Diagram below). We're having intermittent communication issues between Virtual Machines during periods of elevated traffic, for example, during Bing/Google/Baidu/McAfee Secure/etc crawls. The issue lasts a couple minutes and it is not a full blown outage; some requests work perfectly fine while others result in errors. I've looked in the system logs on the VMs and host system but there's nothing indicating failure (other than some ASP.net ODBC errors on the Web VM because it can't reach the database host).
Our old setup with a single 8-year old Windows Server 2k3 web and database server handled all the traffic without a problem, but was limiting our new development abilities. It only had 4GB of RAM and an old 2GHz dual-core processor. Our new server has 32GB of RAM and a quad-core 3.4GHz Xeon. The hardware blows the old stuff out of the water when everything is working. Pages load faster, queries run faster, etc.
The only things I can think of are that traffic is essentially doubled-up on the adapter because the DB and Web are on seperate VMs but share the same Virtual Network, or, there may be a problem with the way our Hyper-V network is configured.
There is a single shared Virtual Switch set up as External. We use a hardware firewall to block ports to the outside world. I've included screenshots of the Network Adapters and current Virtual Switch setup.
I'm not sure which properties should be enabled/disabled on the Host and VMs. The machine has 2 nics, but everything is currently set up on one port. It's been recommended to use one port for admin and the other for the virtual switch, which I'm sure would increase performance when we log into the boxes, but I'm not sure that fixes the current issue.
Can anyone provide guidance on what the Nic properties should be on the host and VMs, or guide me to tweaks to boost network performance?