How to know if you need more cache capacity?

This KB article tells you how to know if you are cache starved i.e. you need more cache capacity.

If you click on the Hosts tab in VirtuCache GUI and then click on a host, you will see stats in the pane below (see picture below). If your cache capacity utilization is 95% or more (field called ‘cache footprint’) and the cache hit % is low (for instance cache hit % is less than 60%) then you know you need more cache capacity. Both fields are highlighted in the picture below.