Hot backup is a method of using archivelog mode to backup database when the database is running. Hot backup is the backup when the system is in normal operation. Once the database is running in archivelog state, it can be backed up.
热备份是在数据库运行的情况下，采用 archivelog mode 方式备份数据库的方法。即热备份是系统处于正常运转状态下的备份。所以，如果你有一个冷备份而且又有热备份文件，在发生问题时，就可以利用这些资料恢复更多的信息。热备份要求数据库在 Archivelog()方式下操作，并需要大量的档案空间。一旦数据库运行在 archivelog 状态下，就可以做备份了。
Hot backup is a method of using archivelog mode to backup database when the database is running. Hot backup is the backup when the system is in normal operation. Therefore, if you have a cold backup and a hot backup file, you can use this data to recover more information in case of problems. Hot backup requires the database to operate in archivelog () mode, and requires a lot of file space. Once the database is running in archivelog state, it can be backed up.
As opposed to cold backup.
1. Hot standby means that under normal conditions, two redundancy work at the same time. When a certain redundancy fails, the system can cut off the fault redundancy, enable the single redundancy mode, and degrade the work
2. Sometimes, we call online backup hot backup and offline data backup cold backup to distinguish two different backup concepts. They can compress more data into existing memory, thus reducing the access to hard disk (called virtual memory) to solve the problem
3. Disk mirroring is a method in which the information written to the physical drive is also written to the second physical drive, also known as hot backup. It is different from the regular copy between hard disks. The image is automatically performed by intelligent controller and some software
Four states of electrical equipment
The operating state refers to that the switch blade is in the closing position, all relay protection and automatic control devices have been put into operation, and the control, signal, closing and protection power supply are supplied
The hot standby state refers to that the switch is disconnected while the switch is still in the closing position, and the others are in the same operation state
Cold standby state – refers to that the switches and knives are all disconnected, the primary equipment is powered off, the control and signal power supply are disconnected, the protection of the equipment itself is put into operation, the pressing plate of other equipment jumps out, and other equipment jumps the pressure plate of the equipment to exit
Maintenance status refers to the switching on power supply on both sides of the equipment to be overhauled on the basis of cold standby, and grounding wires, signboards and safety barriers shall be installed on each side of the overhauled equipment according to the maintenance requirements
Data file backup
(1) Set table space to backup state
(2) Backup the data file of the table space
(3) Restore the table space to normal state
1. It can be backed up at the table space or database file level with short backup time.
2. The database can still be used during backup.
3. It can achieve second level recovery (recovery to a certain point in time).
4. Recover almost all database entities
5. Recovery is fast, in most cases when the database is still working.
1. Do not make mistakes, otherwise the consequences will be serious
2. If the hot backup is not successful, the results can not be used for point in time recovery
3. Because it is difficult to maintain, it is necessary to be careful and not to “end in failure”.
冷备份发生在数据库已经正常关闭的情况下，当正常关闭时会提供给我们一个完整的数据库。冷备份时将关键性文件拷贝到另外的位置的一种说法。对于备份 Oracle 信息而言，冷备份是最快和最安全的方法。冷备份的优点是：
Cold backup occurs when the database has been shut down normally. When the database is shut down normally, a complete database will be provided to us. A term used to copy critical files to another location during cold backup. Cold backup is the fastest and safest way to back up Oracle information. The advantages of cold backup are:
1. Is a very fast backup method (just copy files)
2. Easy to archive (simple copy is enough)
3. Easy to recover to a point in time (just copy the file back)
4. It can be combined with archiving method to restore the “best state” of database.
5. Low maintenance, high safety.