Create a snapshot-consistent group to create snapshots of multiple cloud disks at the same time to back up disk data - Elastic Compute Service

If your business system spans multiple cloud disks on one or more Elastic Compute Service (ECS) instances in the same zone, you can create a snapshot-consistent group to create snapshots for the disks at the same time. This ensures point-in-time consistency and crash consistency of data written to the disks. This topic describes how to create a snapshot-consistent group.

Considerations

Before you create a snapshot-consistent group, take note of the items described in the following table.

Item	Description
Impacts on performance	Within seconds of starting the snapshot creation process, the I/O performance of the cloud disk is affected and can decrease by up to 10%. Once the snapshot upload progresses, the read and write performance of the cloud disk returns to normal. To minimize the impacts on business operations, we recommend that you create snapshots during off-peak hours or when I/O latency is not a concern.
Billing	You can create a snapshot-consistent group free of charge, but you are charged snapshot storage fees based on the size and usage duration of the snapshots created by using the group. For more information, see Snapshots.
Limits	The snapshot-consistent group feature supports only Enterprise SSD (ESSD) series disks (ESSDs, ESSD AutoPL disks, and ESSD Entry disks) for which the multi-attach feature is disabled. You can create a snapshot-consistent group only for cloud disks in the same zone. You cannot specify custom retention periods for snapshots created by using a snapshot-consistent group. By default, the snapshots are retained until you manually delete them. You can create a snapshot-consistent group for multiple ECS instances. Each snapshot-consistent group can contain snapshots of up to 16 cloud disks, including system disks and data disks, and the total capacity cannot exceed 32 TiB in size.

For more information about the limits of snapshot creation, see the limits described in the Create a snapshot topic.

Prerequisites

ECS Snapshot is activated. For more information, see Activate ECS Snapshot.
The cloud disks for which you want to create snapshots are in the In Use state, and the ECS instances to which the disks are attached are in the Running or Stopped state.

Procedure

Go to ECS console - Snapshot-consistent Groups.
In the top navigation bar, select the region and resource group of the resource that you want to manage.
On the Snapshot-consistent Groups tab, click Create Snapshot-consistent Group.

In the Create Snapshot dialog box, configure the parameters described in the following table.

Parameter		Description
Resource Type		Valid values: Instance and Cloud Disk. Default value: Instance. If you set Resource Type to Instance, select one or more ECS instances for which you want to create a snapshot-consistent group. Then, select the cloud disks for which you want to create snapshots from the ECS instances to ensure data consistency. Note If you set Resource Type to Cloud Disk, select a cloud disk for which you want to create a snapshot. For more information, see Create a snapshot.
Select Instances		Select one or more ECS instances for which you want to create the snapshot-consistent group.
Select Cloud Disks		Select the cloud disks for which you want to create snapshots. Note You can select only ESSD-series disks (ESSDs, ESSD AutoPL disks, and ESSD Entry disks) even if cloud disks of other categories are attached to the ECS instances.
Snapshot-consistent Group Name		Enter a name for the snapshot-consistent group.
Advanced Settings (Optional)	Application-consistent Snapshot	Enable Application-consistent Snapshot: You can select this check box to enable the application-consistent snapshot feature. By default, this check box is not selected. Note If your business requires a high level of data consistency, you can enable the application-consistent snapshot feature when you create a snapshot-consistent group. The feature ensures that applications maintain data consistency. For more information, see Create application-consistent snapshots. For information about the limits of the application-consistent snapshot feature, see the Limits section of the "Create application-consistent snapshots" topic.
	Description	Enter a description for the snapshot-consistent group to facilitate management.
	Tag	Specify tag key-value pairs that you want to add to the snapshot-consistent group to facilitate management.

Click OK.
(Optional) On the Snapshot-consistent Groups tab, view the snapshot-consistent group you created in the list or click its ID to view its snapshot details.

References

You can call the following API operations:
- CreateSnapshotGroup: creates a snapshot-consistent group.
- DescribeSnapshotGroups: queries information about snapshot-consistent groups.
- ModifySnapshotGroup: modifies a snapshot-consistent group.
After you create a snapshot-consistent group, you can perform the following operations:
- Use the snapshot-consistent group to roll back cloud disks. For more information, see Roll back disks by using a snapshot-consistent group.
- Use a snapshot in the snapshot-consistent group to perform the following operations:
To prevent unnecessary costs, we recommend that you periodically delete snapshot-consistent groups or snapshots you no longer require. For more information, see the Delete a snapshot-consistent group section of the "Modify or delete a snapshot-consistent group" topic.