VMware vs Microsoft on hypervisor stability and 3rd party drivers

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VMware’s activity on competition is intensifying in this period of the year: after last month’s comments on Citrix HDX performance and Essentials for Hyper-V sales volume, as well as the cost of managing Hyper-V, they focuses on Microsoft hypervisor’s stability.

Eric Gray, Senior Engineer on the VMware Competitive Team, writes on the topic on its personal blog vCritical, suggesting that ESX has a critical advantage over Hyper-V (and Xen and KVM) because Microsoft relies on 3rd party general-purpose drivers while VMware offers hardened, stress-tested drivers — ready for your toughest enterprise workloads.

Gray mentions a presentation performed by the Microsoft Technical Fellow Mark Russinovich, who confirmed that Windows crashes largely depend (70%) by 3rd party driver code (while Microsoft code is responsible only 5% of times).

The benefits vs shortcomings of relying on generic Windows drivers for Hyper-V is a old theme and while this specific article doesn’t add anything new to the discussion (despite it quotes a couple of real-world examples) the comments offer something new.

Ben Armstrong, Program Manager on Core Virtualization at Microsoft, jumps in and offers a different perspective on drivers quality and how it impacts hypervisors stability. He suggests that Microsoft drivers receive more thorough testing and validation than VMware drivers do:

…what is missing here is some scope. Yes, 70% of crashes are caused by drivers – without understanding the % of systems crashing compared to systems deployed this number is accademic.

Think of it this way (leaving out company names):

Company 1: Of 10,000 deployments 1,000 crashed in our code and 700 crashed in the drivers.

Company 2: Of 10,000 deplouments 300 crashed in our code and 700 crashed in the drivers.

Company 1 says: ~40% of crashes happen in the driver code on our system.
Company 2 says: ~70% of crashes happen in the driver code on our system.

Given all of this data – we can actually see that the driver quality is the same (in this hypothetical scenario). Unfortunately in this case we do not have the full numbers on how many deployments VMware / Microsoft has, how many crashes there are total, etc…

The purpose of this presentation (when originally given) was to talk about the health of the Windows ecosystem and platform as a whole. This is why the figure is a comparision of driver crashes to total crashes.

To make an assertion about the quality of drivers on one platform versus another platform – which you need is the percentage of driver crashes compared to total number of deployments.

Neither Microsoft or VMware have provided this information…

The entire comments thread is worth a read.