Copy–only backups are independent backup files that do not disrupt the regular Log Sequence Number (LSN) routine. This means that backup chains and restore sequences won’t be affected by the copy–only backup.
A copy-only backup is a SQL Server backup that is independent of the sequence of conventional SQL Server backups. Usually, taking a backup changes the database and affects how later backups are restored. However, occasionally, it is useful to take a backup for a special purpose without affecting the overall backup and restore procedures for the database. Copy-only backups serve this purpose.
The types of copy-only backups are as follows:
- Copy-only full backups (all recovery models)A copy-only backup cannot serve as a differential base or differential backup and does not affect the differential base.Restoring a copy-only full backup is the same as restoring any other full backup.
- Copy-only log backups (full recovery model and bulk-logged recovery model only)A copy-only log backup preserves the existing log archive point and, therefore, does not affect the sequencing of regular log backups. Copy-only log backups are typically unnecessary. Instead, you can create a new routine log backup (using WITH NORECOVERY) and use that backup together with any previous log backups that are required for the restore sequence. However, a copy-only log backup can sometimes be useful for performing an online restore. For an example of this, see Example: Online Restore of a Read-Write File (Full Recovery Model).The transaction log is never truncated after a copy-only backup.
Copy-only backups are recorded in the is_copy_only column of the backupset table.
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