Latency between IIS and SQL on same physical, two VMs
- by Jerad Rose
I have a single server (2x4 core CPUs, 32GB ram), that is a Windows Server 2012 Hyper V host, and it hosts two guest VMs (also Windows Server 2012 instances). One of them is a web server, the other is a SQL server.
When hitting a page that loops over 50 records, there is noticeable latency. I capture/report the timings of each iteration on the loop, and each iteration is about 20-30 milliseconds. Of course, this amounts to over a second of latency for the whole loop.
I thought maybe SQL needed to be tuned, but running profiler on it, the queries are showing almost 0 duration, so it seems the bottleneck is in transit between the two VMs.
I have both VMs configured to use the actual NIC (vs. using a VNIC), so maybe that's part of my problem.
Also, this is a classic ASP site, so it's using the SQL OLE DB provider, and I'm wondering if that is part of the problem.
This is a new server setup, from an existing Windows 2003/IIS6 server setup where both web and DB run on the same server instance (no virtualization). On that setup, there is no such latency when looping over the cursor like this. But there are so many variables, I'm not sure where to start ruling things out.
