VM high availability

VMs provide compute capabilities. They provide processing power and hosting for applications and services. If the application is deployed on a single VM and that machine is down, then even the application is not available. If the application is composed of multiple tiers and each tier is deployed in its own single instance of a VM, even downtime in a single VM can render the application non-available. Although Azure tries to make even single VM deployments highly available by placing them on different racks as soon as it can, Azure does not ensure or guarantee any SLA. Azure provides an SLA for those VMs that are grouped together in an availability set. It provides a five nines (99.999%) SLA for the availability of VMs if they are part of an availability set and more than two VMs are on that availability set.