Database backup scenarios involve the following concepts: database disk space, data file size, backup data size, and storage data size.

Data size Description
Database disk space The total disk space of a database consists of the available space of the operating system of the server where the database resides and the total space consumed by data files, logs, and operating system files.
Note
  • For an ApsaraDB RDS instance, the storage space that you select when you purchase the instance is included in the total disk space of a database.
  • For a database hosted on an Elastic Compute Service (ECS) instance, the collective storage space of the system disks and data disks that you select when you purchase the ECS instance is included in the total disk space of a database.
Data file size The data file size of a database is equal to the amount of disk space occupied by database data files on the server where the database resides.
You can perform the following operations to view the data file size of a database:
  • To view the data file size of an ApsaraDB RDS instance, log on to the ApsaraDB RDS console. In the left-side navigation pane, click Instances. On the Instances page, find the instance and click Manage in the Actions column. In the left-side navigation pane of the page that appears, click Monitoring and Alerts. On the Monitoring tab of the Monitoring and Alerts page, click Data Usage below the Disk Space (MB) chart.
  • To view the data file size of a database hosted on a Linux server, go to the directory of the data files of the database and run the du -sh command.
  • To view the data file size of a database hosted on a Windows server, open the folder where the data files of the database reside. Right-click the blank area and select Properties.
Backup data size The backup data size of a database refers to the amount of data that you back up by using DBS. The backup data size is based on various factors, such as the database type, backup mode, and backup granularity.
Storage data size The storage data size of a database refers to the amount of data stored in the storage system. The storage data size is based on a variety of factors such as the backup data size, the storage format of backup data, and the compression algorithm.

The database disk space is greater than the data file size. The data file size is greater than the backup data size. The backup data size is greater than the storage data size.