Overview

Usage Notes

Backing up data consumes a few CPUs. Uploading backup files to OBS occupies bandwidth of compute nodes, causing slight latency and jitter.

Backup Methods

GeminiDB Cassandra instances support automated backup and manual backup.

• Automated backup

  You can click Modify Backup Policy on the GeminiDB console, and the system will automatically back up your instance data based on the time window and backup cycle you set in the backup policy and will store the data for the retention period you specified.

  Automated backups cannot be manually deleted. You can adjust their retention period by referring to Modifying an Automated Backup Policy, and backups that expire will be automatically deleted.

• Manual backup

  A manual backup is a full backup of a DB instance and can be retained until you manually delete it. Manual backup can be triggered at any time to meet your service requirements.

  Regularly backing up your database is recommended. If your database becomes faulty or data is corrupted, you can restore it from backups.

  Table 1 Comparison between automated backup and manual backup

  Backup Method	Scenario
  Automated backup	After you set a backup policy, the system automatically backs up your database based on the policy. You can also modify the policy based on service requirements. Either incremental or full backup is supported.
  Manual backup	You can enable full backup for your instance based on service requirements.

  Cross-region and table-level backups are supported based on application scenarios.

  Table 2 Application scenarios

  Method	Scenario
  Cross-region backup	GeminiDB Cassandra API allows you to store backups in the destination region. Then for disaster recovery, you can restore the backups to a new instance in another region. Only an automated full backup is supported.
  Managing Table-level Backups	If a database or table is deleted maliciously or accidentally, you can use backups to restore data. Manual and automated backups are supported.

  Full and incremental backups are created based on data volumes.

  Table 3 Comparison between full and incremental backups

  Backup Type	Full backup	Incremental backup
  Description	All data in an instance is backed up.	Only data that has changed within a certain period is backed up.
  Enabled by Default	Yes	Yes
  Retention Duration	You can specify how many days automated backups can be retained for. If you shorten the retention duration, the new backup policy takes effect for existing backups. Manual backups are always retained even though a GeminiDB Cassandra instance is deleted. They can only be deleted manually.	Incremental backups will be deleted along with automated full backups.
  Feature	All data of your instance is backed up in the current point of time. You can use a full backup to restore all data generated when its backup was created. Full backups can be created automatically or manually.	Incremental data in your instance is backed up since the last full backup. When you use an incremental backup for restoration, the last full backup data and the incremental data generated since then are downloaded. Incremental backups can be created automatically only.
  How to View	Click an instance name. On the Backups & Restorations page, click the Instance-level Backups and Table-level Backups tabs to view the backup size.	Click an instance name. On the Backups & Restorations page, click the Incremental Backup tab to view the backup size.

How Backup Works

GeminiDB Cassandra provides a dedicated node (seed) responsible for managing backups. As shown in the following figure, a GeminiDB Cassandra cluster chooses the seed node for backing up data. The node takes snapshots of data in seconds and then stores them as compressed backups in OBS buckets, without using any store space of your instance. The CPU usage may increase 5% to 15% because uploading backups consumes CPU resources.

Figure 1 Backup process

Backup Storage

Backups are stored in OBS buckets, providing disaster recovery and saving space.

After you purchase an instance, GeminiDB Cassandra API will provide additional backup storage of the same size as you purchased. For example, if you purchase an instance of 100 GB, you will obtain additional backup storage of 100 GB free of charge. If the size of backup data does not exceed 100 GB, the backup data is stored on OBS free of charge. If the size of the backup data exceeds 100 GB, you will be charged based on the OBS billing rules.