Azure Availability Zones, a high-availability solution for mission-critical applications, is now generally available in East US.
Availability Zones are physically separate locations within an Azure region. Each Availability Zone consists of one or more datacenters equipped with independent power, cooling and networking. With the introduction of Availability Zones, we now offer a service-level agreement (SLA) of 99.99% for uptime of virtual machines.
Availability Zones are generally available in select regions.