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Saturday, August 2, 2008

What is HOT / COLD backup?

There is two types of backup we can take for Oracle Database.

1. COLD/OFFLINE/CONSISTENT backup

What is cold backup and why we say "cold" backup?

When database is DOWN, no activity running on database, no one accessing the database. that time taken database backup called "COLD BACKUP". We can also say "OFFLINE" database backup.

In short:

COLD backup equal to OFFINE backup

COLD backup equal to CONSISTENT backup

For COLD/OFFLINE/COSISTENT database backup we must need to SHUTDOWN Oracle Database with the following option.

1. SQL>shutdown normal

2. SQL>shutdown immediate

3. SQL>shutdown transactional;

4. SQL>shutdown abort;

5. CMD>net stop OracleService

For Example of cold backup on any OS platforms.

1. conn with sysdba user.

2. shutdown oracle database

3. copy init.ora, all datafiles, all redologs files, all controlfile to backup location

4. startup oracle database

NOTE: Database doesn't require ARCHIVELOG mode for COLD backup.

2. What is HOT/ONLINE/INCONSISTENT backup?

When database is open, user accessing the database that time we taken backup is called "HOT,ONLINE, inconsistent" backup.

NOTE: Database must require ARCHIVELOG mode for HOT backup.

For HOT backup we have two options

1. RMAN Recovery Manager (Server Managed Backup)

2. User Managed Backup (User Managed backup)

3 comments:

aslamkhalife said...

Cold Backup is not consistent (Good backup) when
SQL>shutdown abort; is performed...

shutdown Abort -
1) Terminate all sessions
2) No rollback of uncommited blocks
3) Terminate the SGA (Instance)
4) Terminates the background processes.

Anonymous said...

I don't recommend backing up database files if shutdown abort is issued.

Im using shutdown immediate, or shutdown normal.

-jabellon

Raj said...

Thanks Mohammed Taj