Annual Interruption Rate

Overview

The Annual Interruption Rate (AIR) is the reliability metric Microsoft Azure uses to measure customer VM disruptions. Azure sets a goal to keep AIR very low, and meeting that goal is the direct business reason live migration is required — because hardware is not perfect, VMs must be moved off failing, predictively-failing, or under-maintenance hardware without the customer observing an interruption. AIR thus functions as the quantitative target that drives the entire NVMe virtual-SSD live-migration standardization effort.