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    Data Management:Logical backup, physical backup, and snapshot

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    Data Management:Logical backup, physical backup, and snapshot

    Last Updated:Feb 21, 2025

    This topic describes the differences among logical backup, physical backup, and snapshot.

    Logical backup, physical backup, and snapshot are common data backup methods.

    • Logical backup: backs up database objects such as tables, indexes, and stored procedures. Commonly used tools include MySQL mysqldump and Oracle exp and imp.

    • Physical backup: backs up database files in operating systems. Commonly used tools include MySQL XtraBackup and Oracle RMAN.

    • Snapshot: creates a fully usable copy of the specified dataset by using the snapshot technology. You can choose to maintain snapshots only on the local server or perform cross-server backup for the snapshots. Commonly used tools include VERITAS File System, Linux LVM, and NetApp NAS.

      Note

      Data Disaster Recovery does not support snapshot-based backup.

    Data Disaster Recovery supports logical backup and physical backup. The following table describes the differences between the two backup methods.

    Item

    Logical backup

    Physical backup

    Full backup

    Data Disaster Recovery splits the data of all tables in a database and executes SQL statements on the database to read the data in multiple threads in parallel.

    A Data Disaster Recovery backup gateway is installed on a database server to back up database files. For more information, see Install a backup gateway.

    Incremental backup

    Data Disaster Recovery reads logs stored in the memory of a database and performs incremental backup based on the logs in real time. This prevents an I/O performance drop that may occur when a full backup is performed. The speed at which database logs are read is adjusted based on the rate at which the logs are generated.

    Feature

    • Finer-grained backup can be performed on databases and tables.

    • Databases are not locked during data backup. This minimizes the impact of data backup on database performance.

    • A database instance can be backed up only as a whole.

    • Data is read from the disks of a database, which affects the I/O performance of the database.

    • In most cases, physical backup and restoration are faster than logical backup and restoration.

      Note

      You can create sandbox instances to use your backup data with ease. For more information, see Data Disaster Recovery sandbox overview.

    Recommended database size

    1 MB to 1 TB

    Larger than 1 TB

    References

    • For more information about the backup methods supported by different database engines, see Database engines and features.

    • Data Disaster Recovery allows you to store backup data in Object Storage Service (OSS) buckets or Data Disaster Recovery built-in storage. For more information, see Built-in storage and OSS.

    • For more information about how to create a Data Disaster Recovery backup schedule, see Create a backup schedule.