With the introduction of new Premium Storage, Microsoft Azure now offers two types of durable storage: Premium Storage and Standard Storage. Premium Storage stores data on the latest technology Solid State Drives (SSDs) whereas Standard Storage stores data on Hard Disk Drives (HDDs).
Premium Storage delivers high-performance, low-latency disk support for I/O intensive workloads running on Azure Virtual Machines. You can attach several Premium Storage disks to a virtual machine (VM). With Premium Storage, your applications can have up to 32 TB of storage per VM and achieve 50,000 IOPS (input/output operations per second) per VM with extremely low latencies for read operations. Premium Storage is currently available only for storing data on disks used by Azure Virtual Machines.
See http://azure.microsoft.com/en-us/documentation/articles/storage-premium-storage-preview-portal/