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"The NO_TRUNCATE option of BACKUP LOG is equivalent to specifying both COPY_ONLY and CONTINUE_AFTER_ERROR." Check the following: https://msdn.microsoft.com/en-us/library/ms191495.aspx •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.** **| NO_TRUNCATE** NO_TRUNCATE Specifies that the log not be truncated and causes the Database Engine to attempt the backup regardless of the state of the database. Consequently, a backup taken with NO_TRUNCATE might have incomplete metadata. This option allows backing up the log in situations where the database is damaged. The NO_TRUNCATE option of BACKUP LOG is equivalent to specifying both COPY_ONLY and CONTINUE_AFTER_ERROR. Without the NO_TRUNCATE option, the database must be in the ONLINE state. If the database is in the SUSPENDED state, you might be able to create a backup by specifying NO_TRUNCATE. But if the database is in the OFFLINE or EMERGENCY state, BACKUP is not allowed even with NO_TRUNCATE. For information about database states, see Database States.