LearnGlossary

What is a disk snapshot in Azure and AWS?

Updated 26 October 2026 · Published by Zoorik

A disk snapshot in Azure or AWS is a point-in-time copy of one disk. You can keep it as a backup, or create a new disk from it.

Azure snapshots and EBS snapshots

  • A snapshot in Azure is a read-only copy of a single managed disk, OS or data.
  • The first EBS snapshot in AWS saves every block written to the volume. Later ones save only new or changed blocks.
  • AWS stores them in Amazon S3. Each can become a new volume in any Availability Zone of its Region.

Snapshots of an Azure VM

A snapshot copies one disk, not a whole virtual machine (VM). Say a VM has an OS disk and two data disks. That takes three snapshots.

A VM with three disks takes three snapshots, one per disk Illustration with no sizes. A box labelled Azure VM holds 3 disks: OS disk, Data disk 1 and Data disk 2. From each disk an arrow, labelled once as copies one disk, points down to its own box: Snapshot 1, Snapshot 2 and Snapshot 3. So 3 disks take 3 snapshots. A bracket under the 3 snapshots reads not coordinated across disks. A VM with three disks takes three snapshots, one per disk Azure VMOS diskData disk 1Data disk 2copies one diskSnapshot 1Snapshot 2Snapshot 3not coordinated across disks
Illustration: each disk in the VM gets its own snapshot, and Azure takes the three separately.

Azure doesn’t coordinate them, so they don’t suit striped disks. Each is crash-consistent: it holds what a crash would leave on the disk.

Why it matters for your cloud cost

  • Azure charges for a snapshot’s used size. A snapshot of a 64 GiB disk holding 10 GiB is charged for 10 GiB.
  • AWS charges for the data an EBS snapshot stores.
  • A forgotten snapshot is charged until it’s deleted.

Amoeba moves a VM’s data disks onto one pool sized to your data, then rightsizes it autonomously. Each move includes a 2-hour soak that watches for disk errors.

After the soak, Amoeba takes a snapshot of each source disk before deleting it: an incremental snapshot on Azure, an EBS snapshot on AWS. It keeps each one for 7 days, then deletes it.

The free assessment works out your own figure.

Read next: Azure disk snapshot cost: incremental vs full snapshots

Sources: Microsoft Learn, “Overview of Azure Disk Storage” (opens in a new tab); Microsoft Learn, “Create a snapshot of an Azure managed disk” (opens in a new tab); AWS, “Amazon EBS snapshots” (opens in a new tab); AWS, “How Amazon EBS snapshots work” (opens in a new tab).

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