I have the following situation. We have a customer with an IBM x3500 server equipped with 16GB of RAM, 2 Intel Quad Core Xeon E5410 processors and three 7200RPM SATA drives in a RAID five array. The server has CentOS 5 (64 bit) installed with VMWare Server 2.
Two virtual machines are configured:
(a) SBS 2008 with 4GB of memory allocated & 2 Processors
(b) Windows 2008 Terminal Server with 8GB of RAM & 2 Processors
The Terminal server is supporting 11 users, acessing it via Wyse thin clients on a LAN, all running Office 2007. Throughout the day, users notice their terminal services sessions become unresponsive. This happens up to ten times per day. I don't have an exact figure on the amount of time they are unresponsive for, but I suspect it is from 5 seconds to perhaps a minute. Sometimes the sessions continue to respond, but, when the users are typing, there is a delay between pressing keys and the characters appearing on their screen.
I have witnessed the Processor utilisation sit at 100% for short amounts of time, but it seems to average about 60%. Memory usage never exceeds 60%.
I have configured Windows System Resource Manager in Per User mode (this seemed to improve performance over per session mode) on the terminal server which made some improvement, but didn't resolve the problem all together.
I have also configured VMWare Server to only use available physical memory, so it shouldn't page.
Checking the event logs on the terminal server shows only a couple of Microsoft Outlook applications hangs.
There has been some suggestion that reducing the allocated processors for the virtual machine to one might improve performance, but I am hesitant to do this as VMWare advise that this can cause "instability" if done after the virtual machines have been created.
I need to determine why the CPU usage is so high at certain times, and what I can do to give the users a better experiance.