While searching for a way to quickly dump a list of VMs and their real memory usage compared to the memory granted, I stumbled upon a VMworld 2006 presentation. In it there were a few rules of thumb that will always come in handy, so I post them here. Partly for the readers of the blog, but mostly for my self :-)
Performance Warnings
Physical host CPU
- Sustained usage of >80%
- Unbalanced usage across cpu’s over time
- processor queue length per cpu > 10
Memory
- Total paging greater than 200-300 I/O per second
I/O
- Most common area for performance issues
- >20ms average sec/transfer time for physical disk
- >3 average queue length
- Split I/O average >1% of total disk I/O
Network (NIC)
- Network queueing regularly occuring