| Cloud server backup | All disks (system and data disks) on an ECS | - Hacker attacks and viruses
You can use cloud server backup to restore data to the latest backup point at which the ECS has not been affected by hacker attacks and viruses. - Accidental data deletion
You can use cloud server backup to restore data to the backup point prior to the accidental deletion. - Application update errors
You can use cloud server backup to restore data to the backup point prior to the application update. - System breakdown
You can use cloud server backup to restore an ECS to the backup point in time prior to system breakdown. | All disks on an ECS are backed up at the same time, ensuring data consistency. In addition, you can configure backup policies for automatic backup. | Creating a Cloud Server Backup | |
| Cloud disk backup | One or more specified disks (system or data disks) | - Only data disks need to be backed up, because the system disk does not contain users' application data.
You can use cloud disk backup to back up and restore data if an EVS disk is faulty or encounters a logical error, for example, accidental deletion, hacker attacks, and virus infection. - Use backups as baseline data.
After a backup policy has been set, the EVS disk data can be automatically backed up based on the policy. You can use the backups created on a timely basis as the baseline data to create new EVS disks or to restore the backup data to EVS disks. | Backup data is stored in OBS, instead of disks. This ensures data restoration upon disk data loss or corruption. Backup cost is reduced without compromising data security. | Creating a Disk Backup | |
| Snapshot | One or more specified disks (system or data disks) | - Routine data backup
You can create snapshots for disks on a timely basis and use snapshots to recover your data in case that data is lost or inconsistent due to unintended actions, viruses, or attacks. - Rapid data restoration
You can create a snapshot or multiple snapshots before an application software upgrade or a service data migration. If an exception occurs during the upgrade or migration, service data can be rapidly restored to the time point when the snapshot was created. For example, if ECS A cannot be started due to a fault occurred in system disk A, you can create disk B using an existing snapshot of system disk A and attach disk B to a properly running ECS, for example ECS B. In this case, ECS B can read the data of system disk A from the disk B. - Rapid deployment of multiple services
You can use a snapshot to create multiple EVS disks containing the same initial data, and these disks can be used as data resources for various services, for example data mining, report query, and development and testing. This method protects the initial data and creates disks rapidly, meeting the diversified service data requirements. NOTE: - A snapshot can only be rolled back to its source disk. Rolling back to another disk is not supported.
- If you have reinstalled or changed the ECS OS, snapshots of the system disk are automatically deleted. Snapshots of the data disks can be used as usual.
| - Legacy snapshots are stored together with EVS disk data to support rapid backup and restore.
- Standard snapshots are stored in OBS, instead of on EVS disks. They can be used to restore data when EVS disks are damaged.
- You can create snapshots to rapidly save disk data as it was at specified points in time. You can also use snapshots to create new disks so that the created disks will contain the snapshot data in the beginning.
| Creating a Snapshot | Rolling Back Data from a Snapshot |
| System disk image | System disk | - Rapid system recovery
You can create a system disk image for the system disk of an ECS before OS change, application software upgrade, or service data migration. If an exception occurs during the migration, you can use the system disk image to change ECS OS or create a new ECS. - Rapid deployment of multiple services
You can use a system disk image to quickly create multiple ECSs with the same OS, thereby quickly deploying services on these ECSs. | A system disk image can help an ECS with OS damaged to quickly change its OS. | Creating a System Disk Image | |
| Data disk image | Specific data disk | Rapid data replication You can use a data disk image to create multiple EVS disks containing the same initial data, and then attach these disks to ECSs to provide data resources for multiple services. | A data disk image can replicate all data on a disk and create new EVS disks. The EVS disks can be attached to other ECSs for data replication and sharing. | Creating a Data Disk Image | Purchasing an EVS Disk |
| Full-ECS image | All disks (system and data disks) on an ECS | - Rapid system recovery
You can create a full-ECS image for the system disk and data disks of an ECS before OS change, application software upgrade, or service data migration. If an exception occurs during the migration, you can use the full-ECS image to change ECS OS or create a new ECS. - Rapid deployment of multiple services
You can use a full-ECS image to quickly create multiple ECSs with the same OS and data, thereby quickly deploying services on these ECSs. | A full-ECS image facilitates service migration. | Creating a Full-ECS Image | Creating an ECS from a Full-ECS Image |
