Hello,
We are experiencing a strange problem with our Exchange 2013 environment.
We have 2 Exchange 2013 servers with both cas and database role.
Clients are being loadbalanced with Citrix Netscaler and the servers are virtual servers running on VMWare Vspshere 6 (but we had the same issue on vsphere 5.5)
Normally all seems to be working fine, but when I activate one of the databases on the other server both servers are unavailable for client connections for 30 minutes or so.
When this happens, both servers are using 100% CPU for the full 30 minutes, the processes causing this are IIS Worker, Exchange store worker and Exchange RPC Client Access
After about 30 minutes things are settling down, cpu usage drops to 30-40% percent and clients can connect again without a problem.
It seems to be related to outlook clients connecting, because doing a failover outside normal office hours, the 100% cpu issue is still there, but only for 30 seconds or so and most ActiveSync connections are also active outside office hours.
Strange thing is, there are only about 500 to 600 outlook clients connected at the same time, can't imagine that that's a lot for exchange to handle.
Anyone has a clue what could cause this?
Thanks in advance.