Borland StarTeam 2009 - Borland Technical Publications

Never backup a transaction log before a database backup is created because the transaction log contains thechanges made to the database after the last backup was created.Never truncate the transaction log manually because it breaks the backup chain. If a transaction log has beentruncated, take a full database backup to start a new backup chain.File BackupsA file or file group backup consists of the backing up of individual data files (or the files in the file group). Afile-based recovery model increases the speed of recovery by allowing you to restore only the damaged fileswithout restoring the rest of the database. For example, suppose a database is comprised of several fileslocated physically on different disks and one disk fails. Only the file on the failed disk needs to be restored andrebuilt using the transaction log backup.File backup and restore operations must be used in conjunction with transaction log backups. For this reason,file backups can only be used with the full recovery and bulklogged recovery models.RecommendationsBorland recommends that you:• Use the full recovery model• Perform a full database backup once every day. For full database sizes greater than 3 GB, it is okay toperform full backups on alternate days. If you perform full backups on alternate days, Borland stronglyrecommends that you create daily differential backups.• Create daily transaction log backups after the completion of the full or differential backup.In addition to this, schedule a transaction log backup every 4 hours.Never truncate a transaction log manually.• In case of a disaster, create a backup of the currently active transaction log.If active transaction log backup is not available (for example, because a media failure for the drive hostingthe transaction logs and drive is not being mirrored), the database cannot be recovered past the last availabletransaction log backup. This would hamper a point-in-time recovery beyond the last available transactionlog backup.• Label the backup tapes correctly.• Keep backup copies in offsite locations.Backing Up Oracle DatabasesAn online or hot backup is a backup performed while the database is online and available for read/writeoperations. Except for Oracle exports, you can only perform online backups when running in ARCHIVELOGmode. An offline or cold backup is a backup performed while the database is offline and unavailable to itsusers.Typically an Oracle DBA uses one or more of the following options to back up an Oracle database.• Export/ImportExports are “logical” database backups that extract logical definitions and data from the database to a file.108 | Backing Up Databases