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About unmanaged (page blobs) and managed disks storage for Microsoft Azure Linux VMs | Microsoft Docs |
Learn about the basics of unmanaged (page blobs) and managed disks storage for Linux virtual machines in Azure. |
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robinsh |
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tysonn |
7be8dd52-98f7-4187-9b78-55197915bc9b |
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11/15/2017 |
robinsh |
Just like any other computer, virtual machines in Azure use disks as a place to store an operating system, applications, and data. All Azure virtual machines have at least two disks – a Linux operating system disk and a temporary disk. The operating system disk is created from an image, and both the operating system disk and the image are actually virtual hard disks (VHDs) stored in an Azure storage account. Virtual machines also can have one or more data disks, that are also stored as VHDs.
In this article, we will talk about the different uses for the disks, and then discuss the different types of disks you can create and use. This article is also available for Windows virtual machines.
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Let's take a look at how the disks are used by the VMs.
Every virtual machine has one attached operating system disk. It's registered as a SATA drive and is labeled /dev/sda by default. This disk has a maximum capacity of 2048 gigabytes (GB).
Each VM contains a temporary disk. The temporary disk provides short-term storage for applications and processes and is intended to only store data such as page or swap files. Data on the temporary disk may be lost during a maintenance event or when you redeploy a VM. During a standard reboot of the VM, the data on the temporary drive should persist.
On Linux virtual machines, the disk is typically /dev/sdb and is formatted and mounted to /mnt by the Azure Linux Agent. The size of the temporary disk varies, based on the size of the virtual machine. For more information, see Sizes for Linux virtual machines.
For more information on how Azure uses the temporary disk, see Understanding the temporary drive on Microsoft Azure Virtual Machines
A data disk is a VHD that's attached to a virtual machine to store application data, or other data you need to keep. Data disks are registered as SCSI drives and are labeled with a letter that you choose. Each data disk has a maximum capacity of 4095 GB. The size of the virtual machine determines how many data disks you can attach to it and the type of storage you can use to host the disks.
Note
For more details about virtual machines capacities, see Sizes for Linux virtual machines.
Azure creates an operating system disk when you create a virtual machine from an image. If you use an image that includes data disks, Azure also creates the data disks when it creates the virtual machine. Otherwise, you add data disks after you create the virtual machine.
You can add data disks to a virtual machine at any time, by attaching the disk to the virtual machine. You can use a VHD that you've uploaded or copied to your storage account, or one that Azure creates for you. Attaching a data disk associates the VHD file with the VM, by placing a 'lease' on the VHD so it can't be deleted from storage while it's still attached.
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- Attach a disk to add additional storage for your VM.
- Create a snapshot.
- Convert to managed disks.