The Two I/O Taxes
The effect of virtualization on throughput
In this short technical briefing on the two I/O taxes in a virtual environment and their effects on throughput, we will cover unhealthy and healthy I/O profiles.
An unhealthy I/O profile is split, small, and random. It is detrimental to performance in Windows environments.
As great as virtualization has been for server efficiency and cost savings, the downside is that it adds complexity to the data path and adds latency.
There are 2 severe I/O inefficiencies contributing to an unhealthy I/O profile. The first is one is the Windows I/O tax. Windows is creating I/O characteristics that are much smaller, more fractured, and more random that they need to be. It’s the perfect trifecta for bad storage performance.
The second I/O penalty is the I/O blender effect, also known as I/O contention. It means the workload from one server or VM is being impacted by its neighboring servers or VM’s. Whether they are related or not, they are sharing the same hardware. Even if they’re not on the same host, they’re sharing the same back-end storage.
You want a healthy, optimum I/O profile. You need contiguous, large, sequential I/O because that is how you can achieve a 30-40% performance.
You can resolve the two I/O taxes in virtual environments. Watch the short technical briefing.