IBM Turbonomic Glossary

An Availability Set is a logical grouping in Microsoft Azure that isolates VM resources from each other to limit the impact of failure.  

Microsoft documentation says that with Availability Sets, “If a hardware or software failure happens, only a subset of your VMs are impacted.”
(Tutorial: Create and deploy highly available virtual machines with Azure PowerShell )

Turbonomic discovers Azure Availability Sets. For each set, it creates a policy that identifies compute tiers to exclude from that set.