• Cloud Server Backup Service

  1. Help Center
  2. Cloud Server Backup Service
  3. User Guide
  4. Service Overview
  5. Basic Concepts

Basic Concepts

Backup Policies

A backup policy is a set of rules for backing up data, including the policy name, policy status, execution time of backup jobs, backup period, and retention rules. The retention rules specify the retention duration and number of retained backups. After an ECS is associated with a backup policy, it can be automatically backed up according to the backup policy.


A backup is generated in a backup operation for a backup object. A backup can be used to restore data of the source backup object. It can be generated in a one-off or periodic method.

CSBS supports one-off backup and periodic backup. A one-off backup job is manually created by users and takes effect for only one time. Periodic backup jobs are automatically driven by a user-defined backup policy.

  • The name of a one-off backup is manualbk_xxxx. It can be user- or system-defined.
  • The name of a periodic backup is assigned automatically by the system. The name of a periodic backup is autobk_xxxx.

Instant Restore

Instant Restore is a feature that provides the instant restoration function for restoring ECS data, which is much faster than the normal restoration function.

Backups generated before the Instant Restore feature is enabled do not support instant restoration. To use the feature, perform a full backup operation and select Enable next to Full Backup when creating the backup. For details, see Creating a CSBS Backup. After Instant Restore is enabled, manual backups for ECSs that have not been backed up automatically support instant restoration, without requiring the selection of Enable next to Full Backup.

No matter whether an ECS has been backup or not, its automatic backups generated after Instant Restore is enabled do not support instant restoration, unless you manually perform a full backup on it.

Backups whose backup type is Common backup do not support instant restoration. Backups whose backup type is Enhanced backup support instant restoration.

Regions and Availability Zones

A region is a geographic area where CSBS works.

Each region comprises one or more AZs and is completely isolated from other regions. AZs within a region can communicate with one another through an internal network, while those in different regions cannot communicate with one another through an internal network.

Public cloud has data centers in different locations. Public cloud CSBS can be used in different locations. You can use CSBS in locations that meet your requirements. For example, you can design applications in a location that is closer to your customers or that can meet legal or other specific requirements.

Each region contains many AZs where power and networks are physically isolated. Each AZ provides cost-effective and low-latency network connections that are unaffected by faults in other AZs. Therefore, deploying CSBS in separate AZs protects your applications against local faults that occur in a specific location.


Projects are used to group and isolate OpenStack resources (computing, storage, and network resources). A project can be a department or a project team. Multiple projects can be created for one account.