This topic describes how to enable PolarDB-O to automatically create backups at specified intervals or manually create backups to prevent data loss in a timely manner. PolarDB-O also allows you to retain backups of a cluster when you delete the cluster.

Backup types

Backup type Description
Level-1 backup (data backup)

Level-1 backups are created based on Redirect-on-Write (ROW) snapshots. These snapshots are stored in a cluster that supports distributed storage. The system does not replicate data when it saves a data block to a snapshot. When a data block is modified, the system saves one of the previous versions of the data block to a snapshot. At the same time, the system creates a new data block that is redirected by the original data block. Therefore, you can create backups within a few seconds regardless of the size of your database storage. Only a small amount of time is required to create and restore level-1 backups. However, level-1 backups take up large storage space.

PolarDB clusters are backed up and restored based on the multi-threading architecture. This improves the efficiency. It takes 40 minutes to restore or clone 1 TB of data based on backup sets (snapshots).

A backup can be retained for seven to 14 days.

By default, the level-1 backup feature is enabled to ensure data security.

The following figure shows the total size of level-1 backups (snapshots).

The total size of level-1 backups
Warning To disable the level-1 backup feature, submit a ticket to contact Customer Services.For more information, see Submit a ticket. However, after you disable this feature, you must bear the risks that may arise. For example, data loss may occur due to user errors.
Level-2 backup (data backup) Level-2 backups are level-1 backups that are compressed and then stored in on-premises storage media. Level-2 backups are slower to restore than level-1 backups. However, the costs incurred for level-2 backups are lower than that of level-1 backups.

Level-2 backups can be retained for 30 to 7,300 days. You can also enable the Retained Before Cluster Is Deleted feature.

By default, the level-2 backup feature is disabled.

If you enable this feature, expired level-1 backups are transferred to on-premises storage media and stored as level-2 backups. The level-1 backups are transferred to level-2 backups at a rate of approximately 150 MB/s.

Note If a level-1 backup expires before the previous level-1 backup is transferred to a level-2 backup, the level-1 backup is deleted and is not transferred to a level-2 backup. For example, the system creates level-1 backups at 01:00 every day for PolarDB clusters and retains the level-1 backups for 24 hours. The system creates Level-1 Backup A at 01:00 on January 1 and creates Level-1 Backup B at 01:00 on January 2. Level-1 Backup A expires at 01:00 on January 2 and starts to be transferred to a level-2 backup. However, Level-1 Backup A stores a large amount of data, and the transfer task is not complete by 01:00 on January 3. Therefore, after Level-1 Backup B expires at 01:00 on January 3, Level-1 Backup B is deleted and is not transferred to a level-2 backup.
Log backup

The log backup feature creates backups by uploading real-time redo logs to Object Storage Service (OSS) in parallel. Based on a full backup (snapshot) and the redo logs generated after the backup is created, you can perform point-in-time recovery (PITR) for a PolarDB cluster. Log backups can prevent data loss caused by user errors and ensure the security of data in the recent period.

Log backups can be retained for 7 to 7,300 days. You can also enable the Retained Before Cluster Is Deleted feature to store data permanently.

Note If you want to restore data to a specific time point, you must include the time required to replay the redo log files. It takes about 20 to 70 seconds to replay 1 GB of redo log data. The total restoration time is the sum of the time required to restore data based on backup sets (snapshots) and the time required to replay the redo log files.

Pricing

The backup and restoration features of PolarDB are free of charge. Only storage fees are charged. Fees are calculated based on the storage space that is consumed by backup files and the amount of time for retaining the backup files. Backup files consist of data files and log files.

Table 1. Pricing
Region Level-1 backup Level-2 backup Log backup
Regions in mainland China USD 0.000464/GB/hour USD 0.0000325/GB/hour USD 0.0000325/GB/hour
Hong Kong (China) and regions outside China USD 0.000650/GB/hour USD 0.0000455/GB/hour USD 0.0000455/GB/hour

Billing methods

Backup type Free quota Billing method
Level-1 backup Database storage usage × 50%

You can view the database storage usage of a cluster on the Overview page of the cluster in the PolarDB console.

Storage fee per hour = (Total physical storage of level-1 backups - Free quota) × Unit price per hour
  • If the physical storage of the level-1 backups does not exceed the free quota, no additional fee is incurred.
  • For more information about the unit price per hour, see Table 1.
  • The following figure shows you how to view Total Physical Storage of Level-1 Backups in the console.Total physical storage of level-1 backups
    Note Total Physical Storage of Level-1 Backups of a PolarDB cluster refers to the sum of the dedicated physical space that is consumed by all level-1 backups, but not the sum of the logical data size. In the preceding figure, part ① shows the sum of the dedicated physical space that is consumed by all level-1 backups, and part ② shows the sum of the logical data size. The data of the PolarDB cluster and multiple level-1 backups (snapshots) are stored in the same physical block. Therefore, they are calculated only once in the bill. For more information about backups, see FAQ about the backup feature.

For example, if the total physical storage of level-1 backups is 700 GB and the database storage usage is 1,000 GB, the storage fee per hour is USD 0.0928.

The fee is calculated based on the following formula: [700 GB - (1,000 GB × 50%)] × USD 0.000464 = USD 0.0928.

Level-2 backup None Storage fee per hour = Total physical storage of level-2 backups × Unit price per hour

For example, if the total physical storage of level-2 backups is 1,000 GB, the storage fee per hour is USD 0.0325.

The fee is calculated based on the following formula: 1,000 GB × USD 0.0000325 = USD 0.0325.

Log backup 100GB Storage fee per hour = (Total physical storage of log backups - 100 GB) × Unit price per hour

For example, if the total physical storage of log backups is 1,000 GB, the storage fee per hour is USD 0.02925.

The fee is calculated based on the following formula: (1,000 GB - 100 GB) × USD 0.0000325 = USD 0.02925.

Backup methods

Backup method Description
Automatic system backup
  • By default, automatic backups are performed once a day. You can configure the start time and the backup cycle for the automatic backup feature. For more information, see Configure the automatic backup feature.
  • Automatic backup files cannot be deleted.
Note To prevent data loss, automatic backups must be performed at least twice a week.
Manual backup
  • You can manually back up data based on your needs. You can create up to three backups for a cluster. For more information, see Manually create a backup.
  • Manually created backup files can be deleted.

Configure the automatic backup feature

  1. Log on to the PolarDB console.
  2. In the upper-left corner of the console, select the region where the cluster resides.
  3. Find the cluster, and then click the cluster ID.
  4. In the left-side navigation pane, choose Settings and Management > Backup and Restore.
  5. Click Backup Settings.
    Backup settings
  6. In the dialog box that appears, configure the following parameters.
    Backup settings-1
    Parameter Description
    Backup Method The default value is Snapshot Backup and cannot be changed.
    Backup Cycle Specifies the backup cycle.
    Note To prevent data loss, automatic backups must be performed at least twice a week.
    Start Time Specifies the start time for an automatic backup.
    Level-1 Backups Retained For Specifies the retention period for level-1 backup files.
    Note Level-1 backup files can be retained for 7 to 14 days.
    Level-2 Backup Enables or disables the level-2 backup feature.
    Note By default, the level-2 backup feature is disabled.
    Level-2 Backups Retained For Specifies the retention period for level-2 backup files.
    Note
    • Level-2 backup files can be retained for 30 to 7,300 days.
    • To permanently retain level-2 backup files, select Retained Before Cluster Is Deleted. This retention period parameter becomes unavailable after you select this option.
    Log Backups Retained For Specifies the retention period for log backup files.
    Note
    • Log backup files can be retained for 7 to 7,300 days.
    • To permanently retain log backup files, select Retained Before Cluster Is Deleted. This retention period parameter becomes unavailable after you select this option.
    When Cluster Is Deleted Specifies the backup retention policy that applies when you delete the cluster.
    • Permanently Retain All Backups: retains all backup files after you delete the cluster.
    • Permanently Retain Last Automatic Backup: retains the latest backup file after you delete the cluster.
    • Immediately Delete All Backups: retains no backup files after you delete the cluster.
    Note
    • If you select the Permanently Retain All Backups or Permanently Retain Last Automatic Backup policy, the system runs an automatic backup task to store all data when you delete the cluster.
    • After you delete the cluster, level-1 backup files are automatically transferred to level-2 backup files. You can go to the Cluster Recycle page to view the stored backup files. For more information, see Cluster recycle bin.
  7. Click OK.

Manually create a backup

  1. Log on to the PolarDB console.
  2. In the upper-left corner of the console, select the region where the cluster resides.
  3. Find the cluster, and then click the cluster ID.
  4. In the left-side navigation pane, choose Settings and Management > Backup and Restore.
  5. On the Backups tab, click Create Backup.
    Create a backup
  6. In the Create Backup dialog box, click OK.
    Note You can create up to three backups for a cluster.

Restore data

For more information, see Restore data.

FAQ

Related API operations

API Description
CreateBackup Creates a full snapshot backup for a specified PolarDB cluster.
DescribeBackups Queries the backup information of a specified PolarDB cluster.
DeleteBackup Deletes the backups of a PolarDB cluster.
DescribeBackupPolicy Queries the automatic backup policy of a specified PolarDB cluster.
ModifyBackupPolicy Modifies the automatic backup policy of a specified PolarDB cluster.