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

Data amount Description
Database disk space The total space consumed by data files, logs, operating system files, and the available space of the operating system of the server where the database resides.
Note
  • For an ApsaraDB RDS instance, the storage space that you select when you purchase the instance is database disk space.
  • For a database hosted on an Elastic Compute Service (ECS) instance, the collective storage space of the system and data disks that you select when you purchase the ECS instance is database disk space.
Data file size 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 database:
    1. On the Instances page, find the instance that you want to view the data file size and click Manage in the Actions column.
    2. In the left-side navigation pane, click Monitoring and Alerts. By default, the Resource Monitoring item is selected on the Standard Monitoring tab.
    3. In the Disk Space line chart, move the pointer over the chart to view Data Usage.
  • To view the data file size of a database hosted on a Linux server, go to the directory of the database files 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 database files reside. Right-click the blank area and select Properties.
Backup data size The amount of data backed up by using Database Backup (DBS). This size depends on a variety of factors such as the database type, backup mode, and backup granularity.
Storage data size The volume of data stored in the storage system. This size depends on a variety of factors such as the backup data size, the storage format of backup data, and the compression algorithm.

The following space sizes are in descending order: database disk space > data file size > backup data size > storage data size.