Microsoft Azure provides you different options for a Virtual machine’s storage environment and one can make between standard versus premium disks.
Standard Disk Storage :
Standard disks are the more cost-effective option because you’re using mechanical HDD storage. These standard disks are stored in an Azure storage account.
There is a standard SSD tier for which you can pay the standard tier price for higher speed solid-state storage, SSD storage.
Standard tier has different performance guarantees, so Microsoft recommends using standard SSD only for dev, test, and for entry-level production applications.
The Metric used for storage in Azure is input/output operations per second or IOPS, and the values that you see for standard storage represents maximum, not expected values for each VHD (virtual hard disk).
Premium Disk Storage :
Premium disks and premium storage are all solid-state drives. So one gets high-speed SSD storage.
The input/output operations per second or IOPS values that are advertised are predictable, expected values. Which is a big differentiator between standard and premium.
There is a different pricing model for premium storage. One has to prepay for all the storage used, which are fixed disk sizes.
An important thing to remember is that your virtual machine storage in Azure is Hyper-V Generation 1 VHD files. So if one is using Gen 2 on-premises, they need to convert from the VHDX to VHD. To ease this Microsoft does have Azure Site Recovery to Azure, and one of the transformations that Azure Site Recovery will do for you is to automatically transform that Generation 2 to Generation 1 disk.
