There are two Distributed In-Memory Caching suites from Microsoft in Azure, namely "Azure Shared Cache" and "Azure Cache".

Azure Shared Cache is a distributed, in-memory, multi-tenant, shared caching solution. It is now deprecated in favor of proper Azure Caching, and will be retired on September 1, 2014.

Azure Cache is a distributed, in-memory, single-tenant, role-based caching solution. Azure Caching is feature-rich such as support for Regions, Tags, High Availability; it also has a wrapper to migrate applications that use Memcached.

Offerings

Azure Cache is available in three offerings

• Azure Redis Cache (Preview)
• Azure Managed Cache Service
• In-Role Cache for Azure Cache

Azure Redis Cache (Preview)

A new cache offering from Microsoft that provides a fully managed Redis caching service. As this service is currently in preview it does not offer an SLA, nor does it come with any attached cost.

Azure Managed Cache Service

Formerly known as Dedicated application has to attach/add 'Cache Worker Roles' (special purpose Azure Worker Roles for Caching) to use Caching. These roles are dedicated solely for 'Caching' purpose, hence the name 'Dedicated'.

In-Role Cache for Azure Cache

Formerly known as Collocated application could use unused memory of their existing roles (Web/Worker) for Caching purposes. In this case, customer can configure how much of their role memory is reserved for Azure Cache. By default this is set to 30%.