Alibaba Cloud Snapshot is an agentless backup service that allows you to create a snapshot or snapshot-consistent group to capture the point-in-time state of data blocks on a disk or disk group. You can use snapshots to restore data, build development and testing environments, or create custom images for batch deployment of business. This topic describes the relevant terms and usage scenarios of snapshots.
Snapshots can be used to create a backup of a disk or disk group. To simultaneously create snapshots for all disks on an Elastic Compute Service (ECS) instance to back up or clone the instance, use the ECS instance backup feature of Cloud Backup.
Introduction
A snapshot is a point-in-time backup of data on a disk. The first snapshot that you create for a disk is a full snapshot. The snapshot contains all of the data blocks that are written to the disk at the time of snapshot creation except for empty data blocks. Subsequent snapshots of the same disk are incremental snapshots that include only the changed and new data blocks that are written to the disk since the previous snapshot was created. For more information, see How snapshots work.
The following figure shows the common operations that you can perform on a snapshot.
Operation | Description | References |
Create a snapshot | You can use the following methods to create snapshots:
Note Instant access snapshots can be created for enhanced SSD (ESSDs) at performance levels 0, 1, 2, and 3 and ESSD AutoPL disks. You can access instant access snapshots within seconds of snapshot creation, instead of after the snapshots are uploaded to Object Storage Service (OSS). For more information, see Use the instant access feature. | |
Roll back a disk | When the system is unresponsive or when accidental changes are made, you can roll back a disk to a previous version by using one of its snapshots. Note You can enable the application-consistent snapshot feature and use application-consistent snapshots for data rollback to ensure that the applications start in a consistent state. For more information, see Create application-consistent snapshots in the ECS console. | |
Create an image from a system disk snapshot | You can create a custom image from a snapshot that contains the operating system and data of an ECS instance. Then, you can use the custom image to create multiple instances that have identical application environments. | |
Create a disk from a snapshot | A single snapshot can be used to create multiple identical disks. Note You can use a snapshot to create disks across zones. | |
Copy a snapshot to a different region | When a snapshot is copied from one region to another, a copy of the snapshot is created in the destination region. | |
Share a snapshot | You can share snapshots with other Alibaba Cloud accounts or within your organization based on resource directories. Other Alibaba Cloud accounts can use your shared snapshots to quickly create disks to meet daily O&M requirements. |
Billing
For information about the billing of snapshots, see Snapshots.
Limits
For information about the limits and quotas of snapshots, see the Snapshot limits section in the "Limits" topic.
Scenarios
Daily data protection
You can create automatic snapshots for a disk to back up data on a periodical basis and retain the snapshots for a specific retention period. This way, you can restore the disk from one of the snapshots when required.
Disaster recovery and fault tolerance
Before you perform O&M operations (such as configuration change, upgrade, and migration) on ECS instances and disks, you can create manual snapshots to back up data. This way, if an issue occurs, you can restore your business from the snapshots to ensure business continuity.
Building development and testing environments
You can create disks from snapshots to build development and testing environments that are isolated from production environments.
Batch deployment of business
You can create custom images from snapshots to batch deploy or upgrade business on multiple sites in an efficient manner.