Since Oracle9i, the LogMiner is
accessible through an Oracle Enterprise Manager GUI, and it provides log analysis
for all datatypes. If the redo log has become corrupted, the LogMiner can now read
past corrupted records as desired in order to analyze the impact on transactions after
the corruption.
Figure 11-8. Database backup and recovery without archived redo logs
Figure 11-9. Database backup and recovery with archived redo logs
Control
Files
Datafiles Online
Redo Logs
1 Full Cold Backup
TIME
T T + 10
2 Disk failure
3
WITHOUT ARCHIVING - The work from T to T+10 is lost
Complete
Restore to
Time = T
WITH ARCHIVING - Minimized restore, no work lost
1 Hot Backup
T T + 10
2 Disk Failure
TIME
Control
Files
Datafiles
4 Replay Changes from Logs
3 Restore Only
Damaged Datafiles
TIME
Archived Redo Logs Online Redo Logs
T T + 10
278 | Chapter 11: Oracle and High Availability
Recovery Manager
Recovery Manager (RMAN), first available with Oracle8, provides server-managed
online backup and recovery. RMAN does the following:
??? Backs up one or more datafiles to disk or tape
??? Backs up archived redo logs to disk or tape
??? Restores datafiles from disk or tape
??? Restores and applies archived redo logs to perform recovery
??? Automatically parallelizes both the reading and writing of the various Oracle
files being backed up
RMAN performs the backup operations and updates a catalog (stored in an Oracle
database) with the details of what backups were taken and where they were stored.
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