Check whether the oracle database is in archive Mode

[1] 1. select name, log_mode from v $ database; NAME LOG_MODE ------------------ ------------------------ query noarchivelog 2. use the archive log list Command Database log mode No Archive Mode Automatic archival Disabled Archive destination/data/oracle/product/10.2.0/db_1/dbs/arch Oldest online log sequence 739 Current log sequence 741 what is Oracle archive mode? Oracle databases have the combined machine redo log, this log records the changes made to the database, such as insertion, deletion, and data update. All these operations are recorded online. In the log. Generally, a database must have at least two online redo log groups. When an online redo log group is full, log switching occurs. At this time, online redo log group 2 becomes the currently used log. When online redo log group 2 is full, log switching occurs again. Write online redo log group 1, and then repeat it. If the database is in non-archive mode, online logs are discarded during Switching. In archive mode, logs are archived When switching. For example, currently online redo log 1 is used. When 1 is full, log switching occurs and online redo log 2 is started, at this time, the content of online redo log 1 will be copied to another specified directory. This directory is called the archive directory, and the copied file is called the archive redo log. You can perform catastrophic recovery only when the database is running in archive mode. 1. the difference between the archive log mode and the non-archive log mode is that only cold backup can be performed in non-archive mode, and only full backup can be performed during recovery. data during the last full backup to system error cannot be recovered. archive mode supports hot backup, Incremental backup, and partial recovery. you can use archive log list to check whether the current mode is ARCHIVE or non-ARCHIVE. configure the database archive Mode 1. change non-archive mode to archive mode: 1) SQL> conn/as sysdba (connect to the database as DBA) 2) SQL> shutdown immediate; (close the database immediately) 3) SQL> startup mount (start the instance and load the database, but do not open it) 4) SQL> alter database archivelog; (change the database to archive mode) 5) SQL> alter database open; (Open the database) 6) SQL> alter system archive log sta Rt; (enable automatic archiving) 7) SQL> exit (exit) make a full backup, because the backup logs generated in non-archive log mode are no longer available in archive mode. this step is not very important! 2. change archive mode to non-archive mode: 1) SQL> shutdown normal/IMMEDIATE; 2) SQL> startup mount; 3) SQL> alter database noarchivelog; 4) SQL> ALTER DATABASE OPEN; 3. enable automatic archiving: In LOG_ARCHIVE_START = TRUE archive mode, the log file group cannot be overwritten. When the log file is full, if the file is not archived manually, the system suspends, until the archiving is completed. at this time, you can only read but not write. shut down and restart the archiving LOG process SQL> archive log stop SQL> ARCHIVE LOG START 4. manual archiving: LOG_ARCHIVE_START = FALSE archiving of the current log File SQL> alter system archive log current; SQL> ALTER System archive log sequence 052; archive all log files SQL> alter system archive log all; change the archive log target SQL> ALTER SYSTEM ARCHIVE LOG CURRENT TO '& path'; 5. archive mode and non-archive mode are reversed in step 1. 6. configure multiple archiving processes Q: When do I need to use multiple archiving processes? A: If the archiving process consumes A lot of time, you can start multiple archiving processes. This is A dynamic parameter and can be modified dynamically using alter system. SQL> ALTER SYSTEM SET LOG_ARCHIVE_MAX_PROCESSES = 10; you can specify up to 10 dynamic performance views related to the archiving process in Oracle9i v $ bgprocess, v $ archive_processes 7. configure archiving targets, multiple archiving targets, remote archiving targets, and archiving log formats. Target LOG_ARCHIVE_DEST_n local archiving targets: SQL> LOG_ARCHIVE_DEST_1 = "LOCATION = D: ORACLEARCHIVEDLOG"; target of remote Archiving: SQL> LOG_ARCHIVE_DEST_2 = "SERVICE = STANDBY_DB1"; Mandatory archiving target. If an error occurs, retry after 600 seconds: SQL> ALTER SYSTEM SET LOG_ARCHIVE_DEST_4 = "LOCATION = E: oraclearchivedlog mandatory reopen = 600 "; OPTIONAL archiving target. If an error occurs, discard Archiving: SQL> ALTER SYSTEM SET LOG_ARCHIVE_DEST_3 =" LOCATION = E: ORACLEARCHIVEDLOG OPTIONAL "; archiving target status: close archiving target and open archiving Target 1 SQL> alter system set LOG_ARCHIVE_DEST_STATE_1 = DEFER open archiving Target 2 SQL> ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_2 = ENABLE archive log format LOG_ARCHIVE_FORMAT 8. obtain archived LOG information V $ ARCHIVED_LOG V $ ARCHIVE_DEST V $ LOG_HISTORY V $ database v $ ARCHIVE_PROCESSES archive log list;