Issues accessing ERP Application in VM from 2003 Terminal Server NLB
I've been going around in circles with this, so I thought I'd try my luck here...
So, the situation is as follows: We have users that log into a 2-node Windows Server 2003 Terminal Server NLB (physical servers). From there, they access a Sage MAS 200 ERP Server that our applications team just migrated from a physical Windows Server 2003 machine to a VM running Windows Server 2008 R2.
Now, our vSphere environment has 4 hosts (Dell PowerEdge R710 machines) all running ESXi 4.1 update 1. We have a vDS set up that about 25 VMs connect to. The vDS has two vmnic uplinks per host (IP hash load balancing) and with the physical switches configured with LACP.
Now that we are in this scenario, users only on the Terminal Server NLB (workstations seem to be fine) are experiencing intermittent connectivity issues with accessing the ERP app. Whereas, the users are able to establish sessions to the Server, the application seems to be having issues loading data. Again, it's hit or miss... some connection attempts are successful and some aren't.
Our application team has been pouring over the Server, making performance tweaks. Given the VM specs, it should be running fine. There are about 100 workstations accessing the app with no problem and about 40 Terminal Server users that are experiencing this issue.
We have some tier 1 apps running in the VM environment with no issues, providing access to thousands of users, so, I'm guessing that there is some specific application incompatibility, even though the ERP vendor says there shouldn't be.
Again, just thought I would throw this out to the community here to see if anyone had any suggestions.