-
Anonymous users2024-02-06Hot Standby A hot backup is a method of backing up a database in archivelog mode when the database is running. So, if you have a cold backup from last night and a hot backup file for today, you can use it to recover more information if something goes wrong. Hot backup requires the database to be operated in archivelog mode and requires a large amount of archive space.
Once the database is running in the archivelog state, it is ready for backup. The command file for hot standby consists of three parts:
1 Data files: Backup of one tablespace and one tablespace.
1) Set the tablespace to the backup state.
2) Back up the data files in the tablespace.
3) The recovery tablespace is in a normal state.
2. Back up the archive log file.
1) Temporarily stop the archiving process.
2) log those files that are in the archive rede log target directory 3) Restart the archive process.
4) Back up the archived redo log file.
3 The advantages of using the alter database bachup controlfile command to back up the hot backup of control files are:
1 Can be backed up at the tablespace or database file level for a short period of time.
2 The database is still available at the time of backup.
3 Recovery in seconds (recovery to a certain point in time) can be achieved.
4 Recovers almost all database entities.
5 Recovery is fast and in most cases the recovery is still working while the love database is still working.
The disadvantages of hot sparing are:
1 Don't make mistakes, or the consequences will be serious.
2 If the hot backup is not successful, the results obtained cannot be used for point-in-time recovery3 Because it is difficult to maintain, special care should be taken not to "end in failure".
-
Anonymous users2024-02-05Hot backup is a synonym for "backup" and refers to the fact that the data being backed up can still be accessed by the application during the backup process. Backups of data collections are typically done using a cold image of the data.
-
Anonymous users2024-02-04Cold standby (offline backup): Backups are performed when the database is stopped.
Warm backup: A global readlock backup is added when the database is running in front of the data to ensure the consistency of the backup data, but it has an impact on performance.
Hot standby process. When the backup starts, the log sequence number (LSN) of the redo log is recorded.
Copy files in both shared and independent tablespaces.
After the replication is complete, the log sequence number (lsn) of the redo log is recorded again.
The redo log generated at the time of backup is copied by the log sequence number recorded earlier.
Advantages of cold standby. Backing up is simple, you only need to copy the relevant files.
Recovery is simple and fast, and you don't need to rewrite any SQL statements or rebuild your index.
Duplicate Qiaoqiao. Database replication works by redoing and applying binlogs to the slave database in real time and asynchronously.
-
Anonymous users2024-02-03Hot backup allows you to back up the tablespace when the database is not down, and cold backup is a backup that must be copied from the tablespace after the database is shut down and the operating system commands are used.
Hot backup is suitable for important databases, such as 7x24 production systems, and can ensure that the database can be restored to any point in time in combination with archive logs in the event of a crash without data loss.
The cold backup has a problem with the database.
All new data and modification records cannot be restored only to the point in time when the backup is completed and the database needs to be restored.
Hot backup can only be carried out in archive mode, cold backup does not need archive mode, archive mode will have a certain impact on system performance, especially disk IO, but compared with the benefits and security of archive, I believe that most DBAs will choose archive mode.
-
Anonymous users2024-02-02Hot backup is used for databases in archive mode while the database is still in a working state.
Cold backup, on the other hand, refers to the backup of a database after it is shut down, and is applicable to databases of all modes.
The advantage of hot backup is that when backed up, the database can still be used and the database can be restored to any point in time.
The advantage of cold backup is that it is fairly simple to perform backup and recovery, and because the cold backup database can work in non-archive mode, the database performance will be slightly better than that of archive mode. (because you don't have to write the archive log to your hard disk).
Cold rolling is a cold working process for steel bars that has emerged in recent years. It is to roll the surface of the round steel bar out of the pattern at room temperature. This can improve the hardness and surface grip of the rebar. >>>More
I usually soak oatmeal, ready-to-eat, very convenient, I think it's good to eat more of this kind of coarse grain, and it's more delicious with brown sugar. Of course, breakfast was hot and didn't hurt the stomach. It is recommended to drink a glass of warm water before breakfast.
Microwave heating starts from the inside, so when the whole steamed bun is fully heated, the water in the center is gone. >>>More
Definition of the phenomenon of supercooling:
During crystallization, the actual crystallization temperature is lower than the theoretical crystallization temperature. At a certain pressure, when the temperature of the liquid is lower than the freezing point of the liquid at that pressure, the phenomenon that the liquid still does not solidify is called supercooled phenomena of liquid. The liquid at this point is called supercooled liquid, which is a thermodynamic condition. >>>More
Comet material is mainly composed of water, ammonia, methane, cyanide, nitrogen, carbon dioxide, etc., while the comet nucleus is composed of a mixture of water, carbon dioxide (dry ice), ammonia, and dust particles that have condensed into ice, making it a "dirty snowball".