Local snapshots provide complete copies of disk data at specific points in time and are an important method for disaster recovery. Local snapshots are stored in the same storage cluster as their source disks for fast backup and recovery of disk data. When disk data is lost, you can use a snapshot to restore the disk data to the point in time when the snapshot was created.
Local snapshots can back up disk data within seconds, which reduces waiting time for business. Local snapshots are applicable to the following scenarios:
- Backup of key business systems that contain a large amount of data, such as databases, containers, and SAP High-performance Analytic Appliance (SAP HANA).
- Backup of data before you perform high-risk operations to reduce waiting time, such as replacing system disks, resizing disks, and updating system patches.
Differences between local snapshots and normal snapshots
Compared with normal snapshots, local snapshots are created in less time and are stored in a different location for quick disk rollback. The following table describes the differences between local snapshots and normal snapshots.
|Snapshot type||Storage location||Disaster recovery scope||Applicable scope||Data synchronization speed||Business recovery|
|Normal snapshot||Stored in Object Storage Service (OSS) buckets that are located in the same region as the snapshot||Region-level, geo-disaster recovery||All disk categories||Slow, within minutes||Snapshots are used to roll back or create disks to recover data and restore the business.|
|Local snapshot||Stored in the same cluster as the source disk (the disk from which the snapshot was created)||Zone-level, zone-disaster recovery||Only enhanced SSDs (ESSDs)||Fast, within seconds|
For more information about snapshot types, see Snapshot overview.
The local snapshot service is commercially available as of July 8, 2020. For information about the billing methods and prices of local snapshots, see Snapshots.
- Local snapshots cannot be created for encrypted ESSDs.
- Up to 10 local snapshots can be retained for each ESSD.
- Local snapshots can be created only for ESSDs.
- After an ESSD is re-initialized, you cannot use local snapshots created before the re-initialization to roll back the ESSD.
- After an ESSD that is used as a system disk is replaced, you cannot use its local snapshots to roll back the replacement ESSD.
|Operation||Supported||References||Related API operation|
|Create a local snapshot||Yes. You can create a local snapshot only for an unencrypted ESSD.||Create a local snapshot||CreateSnapshot|
|Query the size of a local snapshot||Yes||View the snapshot size||DescribeSnapshots|
|Roll back the disk to restore data to the point in time when the local snapshot was created||Yes||Roll back a disk by using a snapshot||ResetDisk|
|Create another disk from the local snapshot||Yes. You can use a local snapshot to create only an ESSD, and the disk size must be equal to the snapshot size.||Create a disk from a snapshot||CreateDisk|
|Create a custom image||No||N/A||N/A|
|Configure local snapshots to be released along with their source disks||No. You can configure only automatic snapshots to be released along with their source disks.||N/A||N/A|
|Encrypt local snapshots||No||N/A||N/A|
|Use an automatic snapshot policy to automatically create local snapshots||No||N/A||N/A|
|Delete a snapshot||Yes. We recommend that you delete local snapshots that are no longer needed to maintain a sufficient quota for new local snapshots.||Delete a snapshot||DeleteSnapshot|