Automatic snapshot policies - Elastic Compute Service - Alibaba Cloud Documentation Center

You can create an automatic snapshot policy and associate the policy with cloud disks to create snapshots for the disks on a regular basis. This protects disk data and reduces the risk of data loss due to irregular snapshot creation.

Use scenarios

You can use an automatic snapshot policy to create snapshots for cloud disks on a regular basis and retain the snapshots for a specific period of time. This way, you can back up disk data on a regular basis, prevent data loss or application system failures caused by accidental deletion or issues such as ransomware, and ensure that disk data can be quickly restored for business continuity.

Operations

The following figure shows the common operations that can be performed for automatic snapshots from the time when an automatic snapshot policy is created until the time when the automatic snapshots are deleted.

Operation	Description
Create an automatic snapshot policy	Create an automatic snapshot policy and specify when to create automatic snapshots and how long to retain the snapshots.
Configure an automatic snapshot policy for a cloud disk	After you associate an automatic snapshot policy with cloud disks, the system automatically creates snapshots for the disks based on the schedule specified in the policy to back up disk data.
Modify an automatic snapshot policy	You can modify the parameters in an automatic snapshot policy, such as the creation time and retention period of automatic snapshots, based on your business requirements.
Create automatic snapshots on a regular basis	The system automatically creates snapshots for a cloud disk based on the schedule specified in the automatic snapshot policy associated with the disk.
Delete an automatic snapshot policy	You can delete automatic snapshot policies that you no longer require.
Delete a snapshot	An automatic snapshot can be deleted in the following scenarios: You manually delete an automatic snapshot. This does not affect the creation of automatic snapshots based on the associated automatic snapshot policy. If the Delete Automatic Snapshots While Releasing Disk attribute is enabled for a cloud disk, the automatic snapshots of the disk are automatically deleted when the disk is released. When the retention period specified in the associated automatic snapshot policy for an automatic snapshot ends, the snapshot is deleted. If the maximum number of automatic snapshots is reached, the oldest automatic snapshots are automatically deleted when new automatic snapshots are created.

Billing

You are not charged for creating an automatic snapshot policy. However, you are charged for snapshot storage based on the snapshot capacity and usage duration. For information about the billing of snapshots, see Snapshots.

Limits

When you use an automatic snapshot policy to create automatic snapshots, take note of the limits described in the following table.

Limit	Description
Snapshot quotas	Up to 100 automatic snapshot policies can be retained per region per account. Only one automatic snapshot policy can be associated with each cloud disk. Up to 1,000 automatic snapshots can be retained per cloud disk. Note If the maximum number of automatic snapshots is reached, the oldest automatic snapshots are automatically deleted when new automatic snapshots are created.
Categories of block storage devices	You cannot create snapshots for local disks or elastic ephemeral disks.
Others	The following limits are imposed on manual and automatic snapshots: If a snapshot is being manually or automatically created for a cloud disk when the point in time specified in the associated automatic snapshot policy is reached, the automatic snapshot cannot be created based on the policy at the point in time. An automatic snapshot is created for the disk at the next point in time specified in the automatic snapshot policy. If an automatic snapshot is being created for a cloud disk, you cannot create a manual snapshot for the disk. Wait until the automatic snapshot is created.

Differences between automatic snapshots and manual snapshots

Automatic and manual snapshots are point-in-time backups of disk data. The following table describes the differences between the creation methods and snapshot names of automatic snapshots and manual snapshots.

Item

Automatic snapshot

Manual snapshot

Creation method

Automatic snapshots are created based on automatic snapshot policies.

After you create an automatic snapshot policy and associate the policy with cloud disks, the system automatically creates snapshots for the disks based on the schedule specified in the policy.

Manual snapshots are manually created.

You can create snapshots for cloud disks and configure snapshot parameters based on your business requirements.

Snapshot name

The name of an automatic snapshot is automatically generated.

The name of an automatic snapshot starts with auto2.0 and is in the auto2.0_yyyyMMdd_SnapshotPolicyId format.

auto2.0: the prefix contained in the name of an automatic snapshot.
yyyyMMdd: the date on which the automatic snapshot is created. yyyy indicates the year, MM indicates the month, and dd indicates the day.
SnapshotPolicyId: the ID of the automatic snapshot policy based on which the automatic snapshot is created.

The name of a manual snapshot is specified when the snapshot is created.