This topic provides answers to commonly asked questions (FAQ) about the backup feature of PolarDB for MySQL.

  • Is the total physical storage space of level-1 backups equal to the size of all the snapshot backups?
    No, the total physical storage space of level-1 backups is not equal to the size of all the snapshot backups. The total physical storage space of level-1 backups is displayed in the ① section, as shown in the following figure.The total physical storage space of level-1 backups
  • Why is the total physical storage space of level-1 backups smaller than the size of a single backup?

    The storage space of level-1 backups in PolarDB is measured by using two methods: logical storage space of each backup and physical storage space of all the backups. PolarDB uses snapshot chains to store level-1 backups. The same data blocks are replicated only once. Therefore, the physical storage space of all the level-1 backups is smaller than the logical storage space of all the level-1 backups. In some cases, the physical storage space of all the level-1 backups is even smaller than the logical storage space of a single backup.

  • How are you billed for backups in PolarDB?

    You are billed for the storage space of level-1 backups, level-2 backups, and log backups. By default, the level-1 backup and log backup features are enabled and the level-2 backup feature is disabled. Alibaba Cloud offers some storage space for free to store backup files.

  • What is the billing method of level-1 backups?

    Storage fee per hour = (Total physical storage space of level-1 backups - Database storage usage × 50%) × Unit price per hour. For example, the total physical storage space of level-1 backups of a PolarDB database is 700 GB and the database storage usage is 1,000 GB. Then, the storage fee per hour is calculated based on the following formula: (700 GB - 500 GB) × USD 0.000464/GB = USD 0.0928.

  • Can I use a storage package to deduct the storage fees of backup data?

    No, a storage package can be used to deduct only the storage fees of business data instead of backup data.

References

Back up data