After an initial full backup, an ECS continues to be backed up incrementally by default.
- A full backup backs up the used capacity, that is, all data in the disk. For example, if a 100 GB disk is allocated with 40 GB data, the backup storage space occupies 40 GB, and the backup size is 40 GB.
- A subsequent incremental backup backs up data changed since the last backup. If 5 GB data changed since the last backup, only the 5 GB changed data will be backed up.
CSBS allows you to use any backup (no matter it is a full or incremental one) to restore the whole data of an ECS. By virtue of this, manual or automatic deletion of a backup will not affect the restoration function.
Suppose ECS X has backups A, B, and C (in time sequence) and every backup involves data changes. If backup B is deleted, you can still use backup A or C to restore data.
In extreme cases, the size of a backup is the same as the disk size. The used capacity in a full backup and the changed capacity in an incremental backup are calculated based on the data block change in a disk, not by calculating the file change in the operating system. The size of a full backup cannot be evaluated based on the file capacity in the operating system, and the size of an incremental backup cannot be evaluated based on the file size change.