Use a snapshot-consistent group to create snapshot backups for multiple disks at the same time - Elastic Compute Service

You can use a snapshot-consistent group to create snapshots for multiple cloud disks attached to one or more Elastic Compute Service (ECS) instances in the same zone. 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, review the following considerations.

Notes	Description
Impact on performance	During the first few seconds of snapshot creation, disk I/O may experience jitter (typically not exceeding 10%). When the upload progress is displayed in the Progress column in ECS Console - Snapshots, the read and write performance will return to normal.
Billing	Creating a snapshot-consistent group is free. However, you incur storage fees for the snapshots created in the group, based on snapshot size and retention period. For more information, see Snapshot billing.
Limits	The snapshot-consistent group feature supports only Enterprise SSD (ESSD) series disks (ESSDs, ESSD AutoPL disks, ESSD Entry disks, and ESSD ZRS disks), and the multi-attach feature must be disabled for these disks. Important ESSD ZRS disks can be added to a snapshot-consistent group only with other ESSD ZRS disks. You can create a snapshot-consistent group only for cloud disks in the same zone. You cannot specify custom retention periods for snapshots created using a snapshot-consistent group. By default, the snapshots are retained until you manually delete them. You can create a snapshot-consistent group across multiple ECS instances. However, each group has limits on the number of disks and total disk capacity: China (Hohhot): Up to 128 disks per group, with a total capacity limit of 256 TiB. All other regions: Up to 16 disks per group, with a total capacity limit of 32 TiB. Total concurrent quota: A single disk can have up to 10 concurrent snapshot tasks, including manual snapshots, automatic snapshots, and snapshot-consistent group tasks. Snapshot-consistent group concurrency has the following limits: China (Hohhot), Philippines (Manila), China (Ulanqab), China (Heyuan), China (Guangzhou), Indonesia (Jakarta), Thailand (Bangkok), China (Hong Kong), China (Qingdao), China (Zhangjiakou), China (Beijing), China (Shenzhen), China (Hangzhou), China (Shanghai), Japan (Tokyo), SAU (Riyadh - Partner Region), UAE (Dubai), Germany (Frankfurt), UK (London), Singapore, Alibaba Finance Cloud (Shenzhen), and Alibaba Finance Cloud (Beijing): No per-task limit. You can create multiple snapshot-consistent groups concurrently, subject only to the overall quota of 10 concurrent tasks. Other regions: A single disk allows only one in-progress snapshot-consistent group task. If one already exists, you cannot select it when creating a snapshot-consistent group, even if the total concurrent quota has not been reached.

For more information about snapshot creation, see the Considerations section.

Prerequisites

ECS Snapshot is activated. For more information, see Activate ECS Snapshot.
The ECS instances to which the disks are attached must be in the Running or Stopped state. The disks must be in the In Use 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, set the parameters for the snapshot consistency group.

Parameter		Description
Resource Type		By default, the Instance option is selected, allowing you to select one or more cloud disks from an instance, create a snapshot consistency group, and then create snapshots for the disks in the group to ensure data consistency. Note You can also set Resource Type to Cloud Disk to create a snapshot for a single disk. For more information, see Create a snapshot manually.
Select Instances		Select one or more ECS instances for which you want to create the snapshot-consistent group.
Select Cloud Disks		On the instance, you can select the disks to include in a snapshot consistency group. Note You can select only ESSDs, ESSD AutoPL disks, ESSD Entry disks, and ESSD ZRS disks. ESSD ZRS disks can be added to a snapshot-consistent group only with other ESSD ZRS disks.
Snapshot-consistent Group Name		Enter a name for the snapshot-consistent group.
(Optional) Advanced Settings	Application-consistent Snapshot	Enable Application-consistent Snapshot: By default, this option is not selected. Select it to enable the application-consistent snapshot feature. Note If your business requires strict data consistency, enable the application-consistent snapshot feature when you create the snapshot-consistent group. This feature ensures internal data consistency within applications. For more information, see Create application-consistent snapshots. For limits on the application-consistent snapshot feature, see the Limits section.
	Description	Enter a description for the snapshot-consistent group to help with management.
	Tag	Add tag key-value pairs to the snapshot-consistent group to help manage resources.

Click OK.
Optionally, on the Snapshot-consistent Groups tab, view the snapshot-consistent group in the list or click its ID to view 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:
- Roll back disks using the snapshot-consistent group. For more information, see Roll back disks using a snapshot-consistent group.
- Use individual snapshots in the group to perform the following operations:
To reduce snapshot storage costs, delete snapshot-consistent groups and their snapshots when no longer needed. For more information, see Delete a snapshot-consistent group.