Virtual Machine Disk Types
All Azure virtual machines have at least two disks – a Windows operating system disk and a temporary disk. Virtual machines also can have one or more data disks. All disks are stored as VHDs and the maximum capacity is 1023 gigabytes (GB).
Operating System Disks
Every virtual machine has one attached operating system disk. It’s registered as a SATA drive and labelled as the C: drive by default.
Temporary Disk
Every virtual machine has a temporary disk that is automatically created for you. On Windows virtual machines, this disk is labelled as the D: drive by default and it used for storing pagefile.sys. For more information on how Azure uses the temporary disk, see Understanding the temporary drive on Microsoft Azure Virtual Machines.
Data Disks
Every virtual machine can have data disks to store application data, or other data you need to keep. Data disks are registered as SCSI drives and are labelled with a letter that you choose. The size of the virtual machine determines how the size of the temporary disk and the maximum number of disks you can attach. Data disks are stored in a BLOB in an Azure storage account.
To use Premium storage, you’ll need a DS-series, FS-series, or GS-series virtual machine. You can use disks from both Premium and Standard storage accounts with these virtual machines. Premium storage is only available in certain regions.
Storage spaces can be used to combine multiple disks into a single larger high-performance volume.
Importing and Exporting Disks
If you want to move on-premises data to Azure Storage (or vice versa), there are a variety of ways to do this. One way is the Azure import and export service.
This service is suitable in situations where you want to transfer several TBs of data to or from Azure, but uploading or downloading over the network is not feasible due to limited bandwidth or high network costs.
Scenarios where this would be useful include:
- Migrating data to the cloud. Move large amounts of data to Azure quickly and cost effectively.
- Content distribution. Quickly send data to your customer sites.
- Backup. Take backups of your on-premises data to store in Azure blob storage.
- Data recovery. Recover large amount of data stored in blob storage and have it delivered to your on-premises location.
Additioanal reading
Azure Blob storage