5 Top Performance and Capacity Concerns for VMware - Storage Latency

As I said on Wednesday if it isn’t memory that people are talking to us about then it is 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's 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 above.

On Monday I'll conclude my series with a look at Cluster Trending. Take a look at our VMware workshop running in December http://www.metron-athene.com/services/online-workshops/capacity-management-workshops.html#vmwarevsphere

Phil Bell

Consultant