A snapshot-consistent group is an advanced data protection feature that enables the simultaneous creation of snapshots for a collection of disks. This feature ensures that snapshots accurately represent the data's state at a specific point in time, providing both crash consistency and point-in-time consistency. It is beneficial for scenarios with high requirements for data synchronization and integrity across multiple disks within a single ECS instance or across various ECS instances.
Scenarios
Snapshot-consistent groups are typically used in the following scenarios:
Cluster file systems and database applications
In cluster file systems and database applications that spread across ECS instances, point-in-time consistency and crash consistency are essential. For example, a MySQL cluster with databases distributed over multiple ECS instances, each with several disks, benefits from snapshot-consistent groups by synchronizing data across all disks during backup, preventing recovery failures or data corruption due to asynchronous data.
Distributed application systems
Snapshot-consistent groups aid large websites or multi-application collaborative systems in obtaining consistent snapshots of all associated disks before upgrades, migrations, or failbacks, ensuring uniform system states and traceability.
Batch backup requirements
For periodic backups of multiple ECS instances within the same region, especially for time-sensitive applications, snapshot-consistent groups offer an efficient solution to execute backups while maintaining data consistency, streamlining management, and mitigating risks.
Features
The following table describes common features of snapshot-consistent groups.
Feature | Description | Reference |
Feature | Description | Reference |
Create a snapshot-consistent group | You can create a snapshot-consistent group to simultaneously take snapshots for multiple disks on one or more ECS instances. When a business system involves multiple disks, you can create a snapshot-consistent group to ensure a consistent write order and the crash consistency of business system data. | |
Roll back disks by using a snapshot-consistent group | If system faults occur, such as hardware or software issues, or if data loss or exceptions are caused by accidental operations, you can use a snapshot-consistent group to roll back one or more disks to restore data and ensure data durability and business continuity. | |
Create application-consistent snapshots | Application-consistent snapshots ensure that application data is in a consistent state during snapshot creation. This allows for direct restoration to a consistent application state upon rollback, bypassing complex log rollback procedures and facilitating fast and stable application startup. If you enable the application-consistent snapshot feature when you create a snapshot-consistent group, the system creates an application-consistent snapshot or a file system-consistent snapshot based on the actual scenario. |
Billing
While the snapshot-consistent group feature is provided at no cost, storage fees apply for each snapshot within the group. For more information, see Snapshots.