Low cache hit ratio if RAM assigned to VirtuCache is always full
You would need 5-20% of storage capacity used by all the VMs in the host as cache capacity. This ensures high cache hit ratio (>75%). This is usually not a problem when using SSDs since SSDs are high capacity. However when using host RAM, you might not have adequate amounts of spare RAM on the host. To ensure that you don’t run out of host RAM to make good use of VirtuCache, please check to see that the ‘Cache Hit’ % at the host level is high even if the Cache assigned to VirtuCache is always full .
The below animated gif shows how to monitor these two parameters at the host level, using the VirtuCache GUI. If ‘Cache Hit’ % at the host level is under 75% and the ‘Cache Footprint’ in the same screen is 95% or more (meaning that cache is full), then you know that you need more cache capacity.