Shulou(Shulou.com)06/01 Report--

Principle * *: transfer the log of the source database to the target database and apply it to the target database

Log transfer method: ARCH transfer (redo logs are transferred only when archiving occurs, and data may be lost), LGWR synchronous transfer (log data is written to the local log file and network at the same time, LGWR must wait for the local log file operation and successful delivery over the network before the transaction is committed), LGWR asynchronous transfer (only need to write the local log file to commit the transaction)

Data protection mode: maximum performance (provide as high data protection as possible without affecting the performance of the source database, once the log data is written to the online redo log file of the source database, things are committed), maximum protection (log data must be written to both the online log file of the source database and the standby log file of at least one target library before the transaction is committed, ensuring zero data loss But the cost is the availability of the source database. Once the log data cannot be written to the standby log file (standby redo log) of at least one target database, the source database will be closed) and the maximum available (like the maximum protection mode, the log data needs to be written to both the online log file of the source database and the standby log file (standby redo log) of at least one target library before the transaction can be committed. If the log data cannot be written to the alternate log file (standby redo log) of at least one target library, the source database will not be closed, but will run in maximum performance mode. After the failure is resolved and the delayed log is successfully applied to the target database, the source database will automatically return to the maximum available mode)

How to apply logs on the target database: physical standby, logical standby

Advantages: disaster recovery, data protection, multiple data protection modes, free of charge

Physical DG configuration: 1. Open force logging (the database will record all operations except temporary tablespaces or temporary rollback segments) 2. Create password file: in the same DataGuard configuration, all SYS users of database servers have the same password, which is implemented using orapwd command; 3. Configure standby redo log: in the maximum protection mode and maximum availability mode, when there is real-time apply, you must set standby redo log for the standby database. The setting condition is that standby redo log is generally the same size as primary redo log, and group has at least one more group than primary. It is important to note that in RAC environment, each instance can be understood as a thread. In this case, the corresponding number of group is multiplied by the number of thread (single thread; number of groups + 1) 4. Put the primary database into archive log mode; 5. Create standby database control files, and try not to have structural changes in the primary database during the period from the completion of the creation to the creation of the standby database. 6. Configure the initialization parameter file of the standby database 7. Create a service, aiming at the startup sequence of 8.DG master and slave libraries on win platform: starting the primary library, then the master library; closing the primary library, then the standby library; and 9, opening the standby library.

Data protection mode switching: from low to high, you need to shut down the database and start to mount state, then switch. If it is from high to low, you can switch directly.

Switching between main and standby libraries: there are two ways, one is switchover, the other is failover;, in which switchover is controllable and reversible; among them, failover is a switch in the event of a failure of the main library, which is irreversible

Upgrade of DG: 1. One is to upgrade first, and then single-button DG environment; 2. Upgrade databases and instances

Several methods of migrating data from single instance environment to DG: 1. Use logical export import, that is, exp/imp tool, you can export objects including the entire database, tables, users, using two ways to export, one is the default, the other is the direct path 2. The use of data pump, the use of direct path mode, while supporting parallelism, high efficiency

Backup and recovery of DG: incremental backup using RMAN

DG fault handling: the first idea is alert log; and the second is V$archive_dest

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