A snapshot-consistent group is an advanced data protection feature for creating simultaneous snapshots of multiple disks across one or more ECS instances in the same zone. This process provides both crash consistency and point-in-time consistency for your backup data.
Use cases
Typical use cases for snapshot-consistent groups include the following:
Clustered file systems and database applications
This feature is ideal for business systems deployed on clustered file systems that span multiple ECS instances and require point-in-time and crash consistency for databases or other enterprise applications. For example, in a self-managed MySQL cluster where the database is distributed across several ECS instances, each using multiple disks, a snapshot-consistent group ensures that all disks are synchronized during a full cluster backup. This prevents recovery failures or data corruption caused by out-of-sync data.
Distributed application systems
For large websites or multi-application systems, data is often distributed across different ECS instances with strong logical dependencies. Snapshot-consistent groups allow you to quickly capture consistent snapshots of all related disks before you perform upgrades, migrations, or disaster recovery. This ensures system state uniformity and traceability.
Bulk backup operations
When you need to perform regular backups for multiple ECS instances in the same zone, especially for applications sensitive to data timeliness, snapshot-consistent groups provide an efficient method. This approach ensures high-performance backups while maintaining data consistency, simplifying management and reducing risk.
Features
The following diagram shows the lifecycle of a snapshot-consistent group, from creation to deletion.
Feature | Description |
You can create a snapshot-consistent group to simultaneously create snapshots for multiple disks that are attached to one or more ECS instances in the same zone. | |
If you have strict data consistency requirements, you can enable the application-consistent snapshot feature when you create a snapshot-consistent group. The system then creates either an application-consistent snapshot or a file system-consistent snapshot based on the actual environment. | |
If your system fails due to hardware or software issues, or if you experience accidental data loss, you can use a snapshot-consistent group to roll back one or more disks. This action restores your disk data to the state before the incident, ensuring data durability and business continuity. | |
You can modify the name and description of a snapshot-consistent group. If a group is no longer needed, you can delete it and its associated snapshots to prevent further charges. Important Deleting a snapshot-consistent group permanently deletes all snapshots within it. Before you proceed, ensure that the snapshots are no longer needed. Deleted snapshots cannot be restored. Proceed with caution. |
Billing
Creating a snapshot-consistent group is free of charge. However, you are charged for the snapshots in the group based on their storage size and retention period. For more information, see Snapshot billing.
Limitations
Snapshot-consistent groups have the following limitations:
Item | Description |
Block storage |
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Other limitations |
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