Snapshot overview

Kingsoft Cloud EBS provides the snapshot feature that allows you to create snapshots based on EBS volumes in the EBS console. As a method for data backup, a snapshot is a fully usable copy of data on an EBS volume. A snapshot is independent of the EBS volume based on which it is created. After an EBS volume is deleted, all snapshots created based on the EBS volume still exist. Snapshots are also an important means of disaster recovery. If data loss occurs on an EBS volume, you can use a snapshot to restore data to the point in time when the snapshot was created. Snapshots are incremental backups. A snapshot records only data that has been updated since the last time a snapshot was created for the EBS volume. This not only shortens the process of creating a snapshot, but also reduces storage costs.

The snapshot technology allows you to quickly back up data on an EBS volume at any time. You can also use snapshots to create EBS volumes. This helps you migrate and deploy a large amount of business data at a time.

Snapshots are classified into common snapshots and local snapshots based on the data storage location. The following table describes the differences between the two types of snapshots.

• Common snapshots take longer time to create and roll back than local snapshots, but the disaster recovery based on common snapshots covers wider ranges and has lower costs. Common snapshots are suitable to meet general disaster recovery needs.
• Local snapshots take shorter time to create and roll back than common snapshots. However, the disaster recovery based on local snapshots covers only EBS clusters in the same availability zone as the EBS volume. Therefore, local snapshots are suitable for quick data backup before key operations such as EBS scale-ups and application system upgrades. Compared with a common snapshot, a local snapshot significantly shortens the time that is taken to create a local image and start the KEC instance to which the EBS volume is attached.

Scenarios

• Daily data backup
  By creating snapshots based on EBS volumes, you can back up data on a daily basis. This helps you cope with problems, such as data loss and data inconsistency, that are caused by viruses, misoperations, or hacker attacks.

• Quick data restoration
  If data loss or data inconsistency occurs due to viruses, misoperations, or hacker attacks, or errors occur when you change an operating system, upgrade software, or migrate business data, you can use a snapshot to quickly restore businesses data to the point in time when the snapshot was created.

• Batch deployment of business
  You can use one snapshot to create multiple EBS volumes to provide the same data for different types of business. At the same time, the original data is protected. This meets corporate requirements for efficient and secure business deployment.

Snapshot billing criteria during beta testing

During the beta testing stage of EBS 3.0, you can create snapshots for EBS volumes free of charge. Before Kingsoft Cloud begins to charge fees for creating snapshots, you will be notified of when and how fees are charged. During the beta testing stage, you can create only a limited number of snapshots for each EBS volume.

• Snapshot quota The snapshot quota for an EBS volume indicates the maximum number of snapshots that you can create for the EBS volume free of charge. You can create a maximum of seven snapshots for an EBS volume. Therefore, the total maximum number of snapshots that you can create is 7 × N. N is the number of your EBS volumes, either to be attached or in use, in EBS 3.0. After you reach your snapshot quota for an EBS volume, you cannot create any more snapshot for the EBS volume.
• Snapshot retention policy Your snapshots will be safely kept in the system unless you delete them.