Backup FAQ for ApsaraDB RDS for MySQL

Why is the snapshot backup for my cloud disk instance so large?

The size shown on the Backup and Restoration > Base Backups > Data Backup page in the console is your instance's disk size, not the actual backup size.

See Where can I view my backup usage? to learn how to view your actual backup usage.

How do I view backup data?

You can view backup data on the Backup and Restoration > Base Backups > Data Backup page in the console.

Where can I view my backup usage?

You can view your backup usage on the Basic Information page of your instance.

In the Usage Statistics section, the backup usage field displays the usage for data backups and log backups, including the free quota of 25,600 MB. You can click View Details for more information.

What does backup usage consist of?

Backup usage is the total size of backup sets and binlog files stored within the specified retention period.

Can I delete backup files?

Yes. For more information, see Delete or reduce backups.

Why doesn't my backup usage decrease after I use Upload Binlogs?

The Upload Binlogs feature moves inactive binlog files from the instance's local storage to the backup space. Because the files are moved, not deleted, your total backup usage does not decrease.

How can I reduce my backup usage?

Consider the following methods:

• Reduce the backup retention period.

• Reduce the backup frequency.

• Increase your free backup quota by upgrading your instance's disk size.

Why do backup sizes differ across instances with the same configuration? Why is my data only a few GB, but the snapshot backup is tens of GB?

Instances that use a cloud disk perform snapshot backups. The size of a snapshot backup is calculated based on the total size of all non-empty blocks in storage, not the logical size of the written data. As a result, the size of a backup set can vary significantly, even for instances with identical configurations and backup policies.

• Reason for the difference: If data is written in a scattered pattern (for example, 3 MB of data may be spread across two to four storage blocks), the number of non-empty blocks increases, and the snapshot backup file becomes larger. If two instances have different ratios of non-empty blocks, their backup sizes will differ, even if their total disk size and configuration are the same.

• Note on temporary files: A backup set's size often differs from the total disk usage because disk usage may include temporary files.

How long does a manual backup take for an RDS instance?

The duration of a manual backup depends on several factors:

• Data volume: Larger data volumes take longer to back up.

• Storage type: Backups are typically faster for instances that use a cloud disk. Instances that use a local disk are slower due to I/O limitations.

• Workload: A high database workload during peak business hours can slow down the backup process.

Because these factors vary, backup times are not fixed and depend on your specific data volume and environment. We recommend performing backups during off-peak hours to minimize the impact on production workloads.