Friday, 21 September 2012

vSphere vs Hyper-V showdown - Memory


As promised on Wednesday let’s move on to take a look at Hyper-V.

Memory Details - Hyper-V Memory Balancer Pressure

The graph below looks at average memory from the host perspective –as you can see the pressure goes up to over 100% and then drops back down.
 
 
The pressure is the ratio of memory allocated compared to memory demand. You won’t ever see this go over 100% as this is at host level, as the operating system balancer will kick in and provide memory where it’s needed.
 
Memory Details - Hyper-V Memory Current Pressure
The next chart here is memory pressure from the virtual machine perspective, which is more granular.
 
 
You will see there is a buffer setting that you configure when you set up dynamic memory, and the buffer setting in this case was 20, which kept normal pressure at 80. When the test started you can see that it went way up over 100 which means that the demand was greater than the allocation in the virtual machines. The balancer would then kick in to provide more memory and you can see the pressure oscillating back and forth.

This test showed that the memory balancer is working effectively.
 
Memory Details - Hyper-V Pages Allocated
In this next chart you can see that pages are being allocated dynamically during the test, based on need.
 
 

On Monday I’ve selected a handful of I/O metrics to show you.
 
Dale Feiste
Consultant
 
 
 
 
 

 
 
 

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