Dba_oracle cold backup and hot backup processing (concept)

2014-07-27 Baoxinjian

I. Summary

1. Cold Backup

A cold backup database is a backup of all critical files, including data files, control files, and online redo log files, to be copied to another location after the database is closed.

In addition, cold backups can include backups of parameter files and password files, but these two backups can be selected as needed.

Cold backup is actually a physical backup, a process of backing up a database physical file.

Because cold backups are backed up with all database files except redo logs, they are also a full database backup.

2. Hot Backup

A hot backup is a way to back up a database using archive log mode, in the case of a database run.

Hot backup requires the database to operate in Archive log mode and requires a large amount of file space.

Once the database is in archive log mode, it can be backed up, and when the backup is performed, it can only be done at the data file level or table space.

Ii. Case 1-cold backup

A cold backup occurs when a database problem is only restored to the point at which the backup was made, and the backup finishes to the database when there is a problem requiring recovery, all new data in this time period, modification records cannot be recovered.

Hot backup can only be done in archive mode, cold backup does not require archiving mode, archiving mode will have a certain impact on system performance, especially disk I/O, but with respect to the benefits and security of archiving, I believe most DBAs will choose the archive mode.

1. Advantages:

• Just copy the file and it's a very fast backup method.
• Simply copy the file back and you can restore it to a point in time.
• The combination of a database archiving pattern allows the database to recover well.
• Less maintenance, but relatively high security.

2. Disadvantages:

• The database must be turned off during a cold database backup.
• When a cold backup is used alone, the database can only complete recovery based on a point in time.
• If disk space is limited, cold backups can only copy backup data to other external storage, such as tape, at a slower rate.
• Cold backups cannot be resumed on a per-table or per-user basis.

3. The case is as follows

Another article introduces

Iii. Case 2-hot backup

Hot backup supports backup with no downtime for the database, and cold backups are copies of the tablespace that must be copied using the operating system's commands after the database shutdown.

Hot backup is suitable for important databases, such as 7x24 uninterrupted production systems, while ensuring that the database can be recovered to any point in time when a crash occurs, with no loss of data.

1. Advantages:

• Backup at table space or data file level with short backup times.
• Can reach a second level of recovery (to a point in time).
• Recovery is possible for almost all database entities.
• Recovery is fast and in most cases resumes when the database is still working.
• The database is still available at backup time.

2. Disadvantages:

• It is difficult to maintain, so be careful not to allow "failure to end".
• If the hot backup is unsuccessful, the resulting results are not available for point-in-time recovery.
• No mistakes, otherwise serious consequences.

3. The case is as follows

Another article introduces

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