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.(This includes those which were copied onMonday & Tuesday, as this backup is cumulative and includes theblocks copied at backups taken at the same incremental level as thecurrent backup)." ThursdayA cumulative incremental level 1 backup occurs.This backs up allblocks that have changed since the most recent incremental backup atlevel n-1 or less; in this case the most recent incremental backup at level1-1 or less is the level 0 Sunday backup, so all the blocks changed sinceSunday will be backed up." FridayA cumulative incremental level 2 backup occurs.This backs up allblocks that have changed since the most recent incremental backup atlevel n-1 or less; in this case the most recent incremental backup at level2-1 or less is the level 1 Thursday backup, so all the blocks changed sinceThursday will be backed up." SaturdayA cumulative incremental level 2 backup occurs.This backs up allblocks that have changed since the most recent incremental backup atlevel n-1 or less; in this case the most recent incremental backup at level2-1 or less is the level 1 Thursday backup, so all the blocks changed sinceSunday will be backed up." The cycle is repeated.Image CopiesAn image copy contains a single file (datafile, archivelog, or control file) thatyou can use as-is to perform recovery.An image copy backup is similar to anO/S copy of a single file, except it is produced by an Oracle server process,which performs additional actions like validating the blocks in the file, andregistering the copy in the control file.An image copy differs from a backupset because it is not multiplexed, nor is there any additional header or footercontrol information stored in the copy.Recovery Manager Concepts 7-17 Image copy backups may be written only to disk.If the image copy is of a datafile, then no restore operation is required; a switchcommand is provided to point the control file at the copy and update therecovery catalog to indicate that the copy has been consumed; this isequivalent to the SQL statement ALTER DATABASE RENAME DATAFILE.You can then perform media recovery to make the copy current.An image copy can be restored to another location to prevent the consumption of the copy, but a restore is not strictly necessary because thedatafile can be renamed to the image copy.User-Created Image CopiesImage copies (also known as O/S copies) created by mechanisms other thanRecovery Manager are supported.However, database administrators mustcatalog such O/S copies with Recovery Manager before they can be used in arestore or switch.Support for both closed and open O/S copies is provided.This support is for users who have other mechanisms for creating imagecopies of datafiles.For example, some sites store their datafiles on mirroreddisk volumes.This permits the creation of image copies by simply breakingthe mirrors.After the mirror has been broken, Recovery Manager can benotified of the existence of a new copy, thus making it a candidate for use in arestore.Note that the database administrator must notify Recovery Managerwhen the copy is no longer available for restore (by using the change.uncatalog command).In this example, if the mirror is resilvered (not includingother copies of the broken mirror), you must use a change.uncatalog toupdate the recovery catalog and indicate that this copy is no longer available.Corruption DetectionAs it is an Oracle server process which is performing a backup or copy, theserver process is able to detect many types of corrupt blocks.Each new corruptblock not previously encountered in a backup or copy operation is recorded inthe control file and in the alert log.Recovery Manager queries this information at the completion of a backup andstores it in the recovery catalog.You can query this information from thecontrol file using the views V$BACKUP_CORRUPTION andV$COPY_CORRUPTION [ Pobierz całość w formacie PDF ]
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.(This includes those which were copied onMonday & Tuesday, as this backup is cumulative and includes theblocks copied at backups taken at the same incremental level as thecurrent backup)." ThursdayA cumulative incremental level 1 backup occurs.This backs up allblocks that have changed since the most recent incremental backup atlevel n-1 or less; in this case the most recent incremental backup at level1-1 or less is the level 0 Sunday backup, so all the blocks changed sinceSunday will be backed up." FridayA cumulative incremental level 2 backup occurs.This backs up allblocks that have changed since the most recent incremental backup atlevel n-1 or less; in this case the most recent incremental backup at level2-1 or less is the level 1 Thursday backup, so all the blocks changed sinceThursday will be backed up." SaturdayA cumulative incremental level 2 backup occurs.This backs up allblocks that have changed since the most recent incremental backup atlevel n-1 or less; in this case the most recent incremental backup at level2-1 or less is the level 1 Thursday backup, so all the blocks changed sinceSunday will be backed up." The cycle is repeated.Image CopiesAn image copy contains a single file (datafile, archivelog, or control file) thatyou can use as-is to perform recovery.An image copy backup is similar to anO/S copy of a single file, except it is produced by an Oracle server process,which performs additional actions like validating the blocks in the file, andregistering the copy in the control file.An image copy differs from a backupset because it is not multiplexed, nor is there any additional header or footercontrol information stored in the copy.Recovery Manager Concepts 7-17 Image copy backups may be written only to disk.If the image copy is of a datafile, then no restore operation is required; a switchcommand is provided to point the control file at the copy and update therecovery catalog to indicate that the copy has been consumed; this isequivalent to the SQL statement ALTER DATABASE RENAME DATAFILE.You can then perform media recovery to make the copy current.An image copy can be restored to another location to prevent the consumption of the copy, but a restore is not strictly necessary because thedatafile can be renamed to the image copy.User-Created Image CopiesImage copies (also known as O/S copies) created by mechanisms other thanRecovery Manager are supported.However, database administrators mustcatalog such O/S copies with Recovery Manager before they can be used in arestore or switch.Support for both closed and open O/S copies is provided.This support is for users who have other mechanisms for creating imagecopies of datafiles.For example, some sites store their datafiles on mirroreddisk volumes.This permits the creation of image copies by simply breakingthe mirrors.After the mirror has been broken, Recovery Manager can benotified of the existence of a new copy, thus making it a candidate for use in arestore.Note that the database administrator must notify Recovery Managerwhen the copy is no longer available for restore (by using the change.uncatalog command).In this example, if the mirror is resilvered (not includingother copies of the broken mirror), you must use a change.uncatalog toupdate the recovery catalog and indicate that this copy is no longer available.Corruption DetectionAs it is an Oracle server process which is performing a backup or copy, theserver process is able to detect many types of corrupt blocks.Each new corruptblock not previously encountered in a backup or copy operation is recorded inthe control file and in the alert log.Recovery Manager queries this information at the completion of a backup andstores it in the recovery catalog.You can query this information from thecontrol file using the views V$BACKUP_CORRUPTION andV$COPY_CORRUPTION [ Pobierz całość w formacie PDF ]