I'm trying to determine an odd problem and I have exhausted most of my capacity with no results... so I'm hoping someone has seen this before. I have both random connection problems and repeatable connection problems, and am not sure if they are related.
I have 2 DB servers (windows 2008 r2, SQL2008 r2) set up with mirroring on my application databases with manual failover.
I (was) running both systems on teamed adapters (4 network ports per server). 2 ports for the primary network (a vlan server only network), 1 port for a crossover between boxes (for the mirror), and 1 port to a physically isolated backup network (my big disk-to-disk-to tape system).
A few weeks ago, I suffered a primary network switch failure. We put a replacement switch in place, loaded the vlan configuration, and went on with life. My application started to report random connection failures. These were not reproducible. I added the application server to my backup network (the one the DB is on), but the problem persisted. I then connected directly via crossover to my app box, and all is well for the application. But a crossover is not a long term solution; failover to the other box will require manual network cable moves. Furthermore, I have other systems that connect to this server via the vlan.
Just yesterday, my BI box started having connection problems. I am able to reproduce it; connections *appear* to fail (using ssms connections to test), but ONLY as the service account user. And when it fails, it comes up with a "could not connect" message... but when you close the message, SSMS is actually connected fine.
All of this started after a network switch failure. Switch has been replaced and is in use. I am not sure where else to look for causes to these connection problems