I recently set up some performance monitoring on my Exchange 2010 SP1 servers running the mailbox server role using the counters mentioned at http://technet.microsoft.com/en-us/library/ff367871.aspx. One counter that quickly popped up with an 'alert' was 'MSExchange Store Interface\RPC Requests Outstanding (_Total)'. According to the previously mentioned TechNet document, this counter should never be above 0. In my monitoring I'm harldy ever seeing this counter at 0 on my servers. The only problem...I'm not really sure what this means. The TechNet document doesn't really state any causes for this counter being above 0. Can someone give me an idea? Thanks!

If the server couldnt handle RPC client connections ( Storage, network problems etc...) then that could cause that counter to grow.

Thanks for the reply, but I'm still uncertain of what this counter is telling me. To take a step back...in Exchange 2007 I would monitor the counter 'MSExchangeIS\RPC Requests'. The rule of thumb I used for that counter is that it should be below 25. If it got above that, much as you described, I would start looking for problems with disk performance, network issues, etc. that would keep client requests from being taken care of. I'm monitoring 'MSExchangeIS\RPC Requests' in Exchange 2010 and that counter hardly ever creeps above 1 (usually sits at zero). Furthermore, client connections seem to be working just fine and all of the client related latency counters look good. So...maybe the question I should have asked is what's the difference between 'MSExchangeIS\RPC Requests' and ''MSExchange Store Interface\RPC Requests Outstanding (_Total)'?

Hmmm, thinking about this. I believe the ''MSExchange Store Interface" counters would actually represent the connection between the Hubs and MBX servers as opposed to the "MSExchangeIS" counters which are looking at client connections. In that case, that woudl indicate a problem with message submission.

http://technet.microsoft.com/en-us/library/ff367871.aspx -should help is store counters and store client request counter

http://technet.microsoft.com/en-us/library/ff367871.aspx -should help is store counters and store client request counter Yep. That's the same link that Shawn originally posted.

Makes sense and thanks for the tip. I'll take a closer look at my hub transport servers.