PMON, RECO, and ARCn of oracle 10g Processes

PMON, RECO, and ARCn PMON: processmonitor process Monitoring of oracle 10g processes performs data recovery when the user process is interrupted (abnormal. PMON is responsible for clearing the data buffer pool and releasing resources used by user processes, such as restoring uncommitted transactions, Releasing locks, and deleting dead processes in process columns. PMON periodically checks the status of 'dispatcher 'and server processes, and restarts oracle processes that are terminated abnormally (excluding processes that are intentionally deleted ). PMON is regularly wakened and can be called to check whether it is needed or when other processes discover it is needed. RECO: recovererprocess is a process used when a distributed option is available to restore the process. It automatically resolves faults in distributed transactions. A node RECO background process automatically links to other databases that contain pending distributed transactions, and RECO automatically resolves all pending transactions. Any row that is equivalent to a paused transaction that has been processed is deleted from the suspended transaction table of each database. When the RECO background process of a database server establishes communication with the same remote server, if the remote server is unavailable or the network connection cannot be established, the RECO will automatically connect again after an interval, the RECO background process only appears in the system that allows DISTRIBUTED transactions, and the DISTRIBUTED-TRANSACTION parameter is limited (greater than 0 ). ARCn: Archiverprocess the archive process ARCn will copy and redo log files to the specified storage device after log exchange. Prerequisites for ARCn: 1. The database must be in the archive mode; 2. The database must be automatically archived. Oracle instances can have 10 ARCn processes (ARC0 ~ ARC9), when the number of ARCn processes in the first line is insufficient to handle the workload, the LGWR process starts a new ARCn process, and the colleagues redo the log to record the operations of LGWR starting the new ARCn process. In case of a High-load archiving operation similar to batch loading, you can use the LOG_ARCHIVE_MAX_PROCESSES parameter to specify the number of ARCn transactions. In fact, you can not modify the default value of this parameter (LOG_ARCHIVE_MAX_PROCESSES), because the oracle system will determine the ARCn process demand. The LGWR process starts the ARCn process based on the workload of the database.