5 Top Performance and Capacity Concerns for VMware - Storage Latency

If it isn’t memory that people are talking to us about then it's storage.

Again, it's not advisable to look at kb per second or I/O at the OS. As previously outlined time slicing can skew these figures so it is better to look at these from VMware.

In terms of latency there is a lot more detail in Vmware. You can look at latency from the device and from the kernel.

Kernel

The graph below looks at the individual CPU’s on the hosts. 

You might ask why am I looking at CPU? If there is a spike in latency on the kernel side it is worthwhile to look at CPU on processor 0. ESX runs certain processes on Processor 0 and this can have an impact on anything going through that kernel.

Latency

It is worthwhile to look at:

–       Device latency

–       Kernal latency

–       Total latency

Shown on the graph below. 

On Monday I’ll finish my series by looking at Trending Clusters.

Phil Bell

Consultant