Oracle 11g R2 Process

User process

ps–elf | grep oracleorcl|grep–v grep

Database process

Ps–elf |grep ORACLEORCL

Daemon process

Ps–elf |grep OHA

Large pool: In the SGA, the large pool is an optional buffer area that administrators can configure as needed, requiring large pools as cache space for large-scale input and output and backup processes, such as big Data operations, database backup and recovery operations.

Java pool: The Java pool is an optional buffer, but you must set up a Java pool when you install Java or a Java program, which is used to compile the Java language script.
Five core processes:

DBWN process: Used to write dirty data from the buffer cache to the data file on the hard disk.

What is dirty data, for example I execute the following statement

sql> update emp setsal=sal+100;

The modified data is stored in memory and is not saved to the data file on the hard disk, which is cached in buffer cache and the transaction has not yet been committed, thus modifying data that has not yet been written to the hard disk data file we call dirty data. In fact, when you open a session, use the Scott user connection to view the data in the EMP table as unmodified. So in Oracle, such operations are asynchronous writes, multiple processes can be written simultaneously, multiple accounts will have multiple dbwn processes, in fact, the process is called DMW, the following n is the resulting process identity

sql> update scott.emp setsal=sal+100;

14 rows have been updated.

Sql>

LGWR: The log write process has only one

Triggers the LGWR process when a user commits (commits a transaction)

The LGWR process is triggered when the One-third space in the red log buffer space is exhausted

Before the dirty data is written to disk, the LGWR process writes the log information to the log file, performing such actions every 3 seconds.

The LGWR process cannot have multiple, because the log is written in sequence and cannot be written in parallel, otherwise data recovery cannot be done.

CKPT process: Checking the consistency of the header of all data files and control files is a mechanism to ensure that all modified chunks of data in the data buffer are written to the data file, which is a mechanism for ensuring data integrity. However, after the checkpoint is complete, the CKPT process is responsible for updating the data file and controlling the header information of the file, and saving the checkpoint information to ensure the synchronization of the database log files and data files. The principle is that when the database is restored, only the last checkpoint saved by Ckpt can be found, and then the log information will be re-executed according to the starting position of the recovered data in the log file.

Smon process: If the data file and the control file header are inconsistent, the smon process is triggered. When the instance starts, the Smon process checks that the synchronization information for all data files is consistent with the checkpoint information recorded in the control file, and the instance recovery operation is initiated in an inconsistent order. In fact, the CKPT process is used for the Smon process.

Pmon process: Process monitoring process, Pmon process manages user sessions, this process performs the appropriate action when a session is in trouble. For example, when a user's personal computer restarts when logging on to a database, Pmon can detect the problem, and it also organizes any actions that the user is doing.

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Oracle 11g R2 Process