Azure Disk Storage
The disks that are used for virtual machines are stored in Azure Blob Storage as page blobs. Azure stores two disks for each virtual machine, the actual operating system (VHD) of the VM and a temporary disk that is used for short-term storage. This data is erased when the VM is turned of or rebooted.
There are two different performance tiers that Azure offers, Standard Disk Storage and Premium Disk Storage.
Standard Disk Storage
Standard Disk Storage offers HDD drives to store the data on and is the most cost-effective storage tier from which you can choose. It can only use LRS or GRS for supporting high availability for your data and applications.
Standard Disk Storage offers HDDs and is more cost-effective. Standard Disk Storage can only use LRS or GRS.
Premium Disk Storage
With Premium Disk Storage, your data is stored on SSDs. Not all Azure Virtual Machine series can use this type of storage. It can only be used with DS, DSv2, GS, LS, or FS series Azure Virtual Machines...