What is server cold backup?
A cold backup occurs when the database has been shut down normally, and will provide us with a complete database when shut down normally. A term for copying critical files to another location during cold backup. For backing up Oracle information, cold backup is the fastest and safest method. The advantages of cold backup are:
1. It is a very fast backup method (just copy files)
2. Easy to file (just copy)
3. Easily restore to a certain point in time (just copy the file back)
4. It can be combined with the archiving method to restore the “best state” of the database.
5. Low maintenance, high security.
What is server hot backup?
Hot backup is a method of backing up the database in the archivelog mode when the database is running. So, if you have a cold backup from last night and today’s hot backup file, you can use these data to restore more information when a problem occurs. Hot backup requires the database to operate in Archivelog mode and requires a large amount of archive space. Once the database is running in the archivelog state, it can be backed up. The command file for hot backup consists of three parts:
1. Datafiles are backed up tablespace by tablespace.
(1) Set the tablespace to backup state
(2) Back up the data files of the tablespace
(3) Restore the tablespace to normal state
2. Backup and archive log files
(1) Temporarily stop the archiving process
(2) Those files in the archive rede log target directory under the log
(3) Restart the archive process
(4) Backup archived redo log files
3. The advantages of using the alter database bachup controlfile command to back up the control file hot backup are:
1. It can be backed up at the table space or database file level, and the backup time is short.
2. The database can still be used while backing up.
3. Second-level recovery (recovery to a certain point in time) can be achieved.
4. Can restore almost all database entities
5. Recovery is fast and in most cases loves recovery while the database is still working.
