You can create automatic snapshot policies to create snapshots for disks on the specified schedules. This prevents data loss due to irregular snapshot creation and improves the reliability and stability of the system. Elastic Compute Service (ECS) supports the cross-region snapshot replication feature to ensure that snapshots are available in the event of region-level disasters or failures. This topic describes how to create an automatic snapshot policy.
Considerations
The snapshot service provides a quota of 1,000 automatic snapshots for each disk. If the maximum number of automatic snapshots for a disk is reached and a new snapshot creation task is created, the system deletes the oldest snapshots that were generated by using the automatic snapshot policy.
For a disk that contains a large volume of data, if a snapshot creation task is being executed and the point in time scheduled for another snapshot creation task is due, the system skips the new task. For example, an automatic snapshot policy specifies that automatic snapshots are created at 9:00, 10:00, and 11:00. If a snapshot creation task starts at 9:00 and lasts for 70 minutes to end at 10:10, the system executes the next snapshot creation task at 11:00, instead of 10:00.
Procedure
Log on to the ECS console.
In the left-side navigation pane, choose .
In the top navigation bar, select the region and resource group to which the resource belongs.
On the Snapshots page, click the Automatic Snapshot Policies tab and then click Create Policy.
In the Create Automatic Snapshot Policy dialog box, configure the parameters described in the following tables.
Configure basic policy settings
Parameter
Description
Policy Name
The name of the automatic snapshot policy.
Execution Frequency
The days of the week on which to create automatic snapshots. You can select one or more days from Monday to Sunday.
Execution Time
The points in time at which you want to create automatic snapshots. Automatic snapshots are created within 1 hour after the points in time specified by the Execution Time parameter. You can select one or more on-the-hour points in time from 00:00 to 23:00.
ImportantWhen a snapshot is being created for an Elastic Block Storage (EBS) device, the I/O performance of the device degrades by up to 10%. This can result in a transient I/O speed decrease. We recommend that you create automatic snapshots during off-peak hours.
Retention Period
The retention period of automatic snapshots. Default value: Until Deleted. You can also specify a custom retention period. After the retention period of automatic snapshots ends, the system automatically deletes the snapshots.
Custom Period: Specify a retention period. Unit: days. Valid values: 1 to 65535.
Until Deleted: Created automatic snapshots are retained based on the number of automatic snapshots. After the maximum number of automatic snapshots is reached, the oldest snapshot is automatically deleted when a new snapshot is created.
ImportantIf the remaining snapshot retention period is a few days such as three days, Released After {days} Days appears in the Retention Period column corresponding to the snapshot on the Disk Snapshots tab.
Extend Retention Period: After an automatic snapshot is created, to extend the retention period of the snapshot, you can click the
icon in the Retention Period column corresponding to the snapshot and specify a retention peirod. Alternatively, in the Actions column corresponding to the snapshot, you can choose 
> Extend Retention Period and specify a retention peirod. If you modify the Retention Period parameter for a automatic snapshot policy, the new retention period takes effect only for new automatic snapshots. For information about how to modify an automatic snapshot policy, see Modify an automatic snapshot policy. For example, after you change the Retention Period value from 20 days to 10 days, new snapshots that will be created based on the policy will be retained for 10 days, whereas existing snapshots that were created based on the policy are retained for 20 days.
Configure a cross-region snapshot replication policy
ImportantAfter a snapshot is copied to a destination region, a snapshot copy is generated in the region. You are charged a data transfer fee for the snapshot replication. You are also charged a snapshot storage fee for the snapshot copy in the destination region based on the snapshot size and storage duration. For more information, see Snapshots.
For information about how to copy a snapshot, see Copy a snapshot.
Parameter
Description
Cross-region Snapshot Replication
After you enable cross-region snapshot replication, automatic snapshots created by using the automatic snapshot policy are copied to the destination region for data backup and disaster recovery.
Destination Region
The region to which the automatic snapshots are copied.
Retention Period of Snapshot Copies
The retention period of snapshot copies in the destination region.
Copy and Encrypt
Leave Enable unselected. For an encrypted snapshot, a snapshot copy is created in the destination region and encrypted by using the default service customer master key (CMK) that was created by Key Management Service (KMS) in the destination region. For an unencrypted snapshot, an unencrypted snapshot copy is created in the destination region.
Select Enable. A snapshot copy is created and encrypted by using the specified encryption key in the destination region, regardless of whether the source snapshot is encrypted.
Configure advanced settings
Parameter
Description
Tag
The tags of the automatic snapshot policy. Automatic snapshots created based on the automatic snapshot policy have the specified tags added. Select existing tag keys and values, or enter new tag keys and values. For more information, see Overview.
You can modify the tags of an automatic snapshot policy after the policy is created. For more information, see Edit the tags of an automatic snapshot policy.
Resource Group
The resource group to which the automatic snapshot policy belongs. For more information, see Resource groups.
Click OK.