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

You can create a snapshot-consistent group to create snapshots of multiple cloud disks on one or more Elastic Compute Service (ECS) instances at the same time. If a business system involves multiple cloud disks, you can create a snapshot-consistent group to ensure a consistent write order and crash consistency of business system data. This topic describes how to create a snapshot-consistent group.

Considerations

Before you use the snapshot-consistent group feature, take note of the following items:

To minimize impacts on your business, we recommend that you create snapshot-consistent groups during off-peak hours.
When you create a snapshot-consistent group, do not perform operations that change the status of the involved ECS instances, such as stopping or restarting the instances. Otherwise, snapshots may fail to be created.

Limits

Only Enterprise SSD (ESSD) series disks (ESSDs, ESSD AutoPL disks, and ESSD Entry disks) for which the multi-attach feature is disabled support the snapshot-consistent group feature. For information about the multi-attach feature, see Multi-attach for cloud disks.
You can use the snapshot-consistent group feature only if the ECS instances are in the Running or Stopped state and the cloud disks are in the In Use state.
The cloud disks for which you want to create a snapshot-consistent group must reside in the same zone.
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 cannot exceed 32 TiB in size.

Procedure

Open the dialog box for creating a snapshot-consistent group.
1. Log on to the ECS console.
2. In the left-side navigation pane, choose Storage & Snapshots > Snapshots.
3. In the top navigation bar, select the region where the ECS instance resides.
4. On the Snapshot-consistent Groups tab, click Create Snapshot-consistent Group.

In the Create Snapshot dialog box, configure the parameters. The following table describes the parameters.

Parameter		Description
Resource Type		Valid values: Instance and Cloud Disk. Default value: Instance. If you set the Resource Type parameter 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 for the disks. Note If you set the Resource Type parameter 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 the ECS instances for which you want to create a 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 (ESSD, 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	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 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 that you created in the snapshot-consistent group list or click the ID of the snapshot-consistent group to view the details of the snapshots in the group.
Note
For information about the amount of time required to create a snapshot, see Create a snapshot.
Snapshots that are created by using a snapshot-consistent group have the following characteristics:
- The names of the snapshots are in the following format: Created_from_<ID of the snapshot-consistent group>.
- The instant access feature is automatically enabled for the snapshots.
- The snapshots are permanently retained.

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, periodically delete snapshot-consistent groups that you no longer require or the snapshots contained in the groups. For more information, see Manage a snapshot-consistent group.