What is the difference between online and offline backups?
(for DBA A hot backup is a backup performed while the database is online and available for read/write. Except for Oracle exports, one can only do on-line backups when running in ARCHIVELOG mode. A cold backup is a backup performed while the database is off-line and unavailable to its users. 78. What is the difference between restoring and recovering? (for DBA Restoring involves copying backup files from secondary storage (backup media) to disk. This can be done to replace damaged files or to copy/move a database to a new location. Recovery is the process of applying redo logs to the database to roll it forward. One can roll-forward until a specific point-in-time (before the disaster occurred), or roll-forward until the last transaction recorded in the log files. Sql> connect SYS as SYSDBA Sql> RECOVER DATABASE UNTIL TIME ‘2001-03-06:16:00:00’ USING BACKUP CONTROLFILE; 79. How does one backup a database using the export utility? (for DBA Oracle exports are “logical” database backups (no
A hot (or on-line) backup is a backup performed while the database is open and available for use (read and write activity). Except for Oracle exports, one can only do on-line backups when the database is ARCHIVELOG mode. A cold (or off-line) backup is a backup performed while the database is off-line and unavailable to its users. Cold backups can be taken regardless if the database is in ARCHIVELOG or NOARCHIVELOG mode. It is easier to restore from off-line backups as no recovery (from archived logs) would be required to make the database consistent. Nevertheless, on-line backups are less disruptive and doesn’t require database downtime. Point-in-time recovery (regardless if you do on-line or off-line backups) is only available when the database is in ARCHIVELOG mode.
A hot (or on-line) backup is a backup performed while the database is open and available for use (read and write activity). Except for Oracle exports, one can only do on-line backups when the database is ARCHIVELOG mode. A cold (or off-line) backup is a backup performed while the database is off-line and unavailable to its users. Cold backups can be taken regardless if the database is in ARCHIVELOG or NOARCHIVELOG mode. It is easier to restore from off-line backups as no recovery (from archived logs) would be required to make the database consistent. Nevertheless, on-line backups are less disruptive and doesn’t require database downtime. Point-in-time recovery (regardless if you do on-line or off-line backups) is only available when the database is in ARCHIVELOG mode.
