- In oracle DBA we know that backup is an one of the important concept let us discuss about cold backup.
- There are two types of backup 1) cold backup 2) hot backup
- We need to shutdown the database and we need to take the backup of control file,redo log file, and database file at os level
- In case of database running with No Archive Log mode then we can only go for simple restore after going through crash
- If it is in Archive Log mode we can either go for Simple Restore or restore+recovery
- Simple restore can even be performed by os admin where as recovery required DBA admin
- Recoveries are of two types 1) Complete recovery 2) Incomplete Recovery
- Complete recovery is possible only when we have 1)present Control file 2)current online redo log file
- If any of the above two files missing then we end up with going for instance crash recovery
- Complete recovery is possible in two ways
- Online----Both system and undotbs datafile must be present
- Offline-----Any datafile can be missing
- Instance crash recovery offers three choices
- Until cancel--Apply all the available archives logs against latest cold backup-this is how offers us maximum recovery until time
- We can recover assuming archives are avilable upto time based recovery
- Until SCN number---recover upto specified SCN number using archives logs
- At the end of ICR we must reset logs then only we can open database.
