Understanding Azure Managed Disk Snapshots
Azure Managed Disk Snapshots are full, immutable copies of a managed disk taken at a specific point in time. They are stored as a special type of managed disk and can be used to:
- Backup data for disaster recovery.
- Migrate data to another Azure region.
- Create new managed disks for development or testing.
- Troubleshoot issues by reverting to a previous state.
Key Characteristics:
- Point-in-time copy: Captures the entire disk state at the moment of creation.
- Immutable: Once created, a snapshot cannot be modified.
- Incremental: Only the changed blocks since the last snapshot are stored, optimizing storage costs.
- Regional or Zonal: Can be created within the same availability zone or replicated to another zone for higher availability.
- Independent: A snapshot is independent of the source disk. Deleting the source disk does not affect the snapshot.
How Snapshots Work:
When you create a snapshot, Azure copies all the data blocks from the source managed disk. Subsequent snapshots of the same disk are incremental, meaning only the data blocks that have changed since the previous snapshot are written. This approach significantly reduces storage costs.
Important Note: While snapshots are incremental, they are charged based on the total data stored. For example, if you have 5 snapshots, each storing 10 GB of changed data, you will be billed for approximately 50 GB of snapshot storage, not just the individual changed blocks.
Use Cases:
1. Backup and Disaster Recovery:
Regularly take snapshots of your data disks and OS disks to ensure you have a recovery point in case of data corruption or accidental deletion. These snapshots can be used to restore disks or create new virtual machines.
2. Migrating Data:
Create a snapshot of a disk in one region, then copy that snapshot to another region. From the copied snapshot, you can create a new managed disk in the target region, effectively migrating your data.
3. Creating Test/Development Environments:
Need to test an application update or a new configuration? Create a snapshot of your production disk, then create a new disk from that snapshot. This new disk can be attached to a test VM without impacting your production environment.
4. Troubleshooting and Auditing:
If an issue arises, you can create a snapshot to capture the disk's state at that precise moment. This allows you to investigate the problem without altering the live data, and if necessary, revert to a previous snapshot.
Snapshot Management:
You can manage your snapshots through the Azure portal, Azure CLI, Azure PowerShell, or Azure Resource Manager (ARM) templates. Key management operations include:
- Creating snapshots
- Listing snapshots
- Deleting snapshots
- Creating disks from snapshots
- Copying snapshots across regions
Pricing:
Snapshot pricing is based on the amount of data stored. Standard HDD, Standard SSD, and Premium SSD snapshots have different cost structures. Refer to the Azure Managed Disks pricing page for the most up-to-date information.
Create an Azure Managed Disk Snapshot Manage Azure Managed Disk Snapshots