Storage Latency - Top 5 Performance and Capacity concerns for Vmware

As mentioned on Wednesday If it isn’t memory that people are talking to us about then it is storage.

It's not advisable to look at kb per second or I/O at the OS because, 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, where 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

With Latency, to get a good picture, it is worthwhile to look at: 

–      Device latency

–      Kernal latency

–      Total latency

These are shown together on the graph below. 

I'll be concluding my series on Monday with a look at Trending Clusters. In the meantime there's still time to register and come along to Jamie's webinar on VMware memory on July 23rd http://www.metron-athene.com/services/training/webinars/index.html

Phil Bell

Consultant