DB_WRITER_PROCESSES and LOG_ARCHIVE_MAX_PROCESSES

DB_WRITER_PROCESSES and LOG_ARCHIVE_MAX_PROCESSES

Includescriptionparameter type IntegerDefault value 1 or CPU_COUNT/8, whichever is greater default value 1 or 1/8 Modifiable No Range of values 1 to 20 of the number of CPUs the value Range is 1 to 20 basic No

 

DB_WRITER_PROCESSES is useful for systems that modify data heavily. it specifies the initial number of database writer processes for an instance. note: The DB_WRITER_PROCESSES parameter sets the number of DBWn processes. Because this parameter is a static parameter, You need to restart the database. Modify the value of this parameter. If the value is not larger, set the value based on the idle time during peak CPU usage. For example:

-- Sample the current CPU information [oracle @ bldc01 bolan] $ vmstat 5 procs ----------- memory ---------- --- swap -- ----- io ---- system -- ----- cpu ------ r B swpd free buff cache si so bi bo in cs us sy id wa st12 2 862788 111796 92004 29095088 1 134 130 0 0 0 15 1 83 1 014 1 862772 116024 91992 29092368 6 0 749 6552 14584 57 3 36 4 013 0 862772 136640 92060 29097092 0 814 6392 16218 24140 862772 56 4 36 4 0 9 1 129644 92076 29101512 692 0 7062 14918 22074 862772 54 3 38 4 015 1 118000 91984 29080072 0 4 577 6216 15478 22928 53 4 39 4 010 0 862772 117148 92000 29085192 0 692 7029 16265 24344 862772 4 37 4 013 0 113464 92012 29081772 676 0 6954 13775 20328 58 3 35 4 0 -- view the current oracle Server CPU count SQL> show parameter cpu_count; name type value contains invalid parameter cpu_count integer 16 -- view the parameter VALUE of db_writer_processes SQL> show parameter db_writer_processes; NAME TYPE VALUE contains parameter ---------------------------- db_writer_processes integer 2

 

From the above information, we found that the number of CPU processes has been maintained at around 12, and frequent waiting processes occur, so the database is not suitable for adjusting the DB_WRITER_PROCESSES parameter.

LOG_ARCHIVE_MAX_PROCESSESProperty DescriptionParameter type IntegerDefault value 2 default value: 2 Modifiable alter system Range of values 1 to 30 value Range: 1-30Basic No

 

LOG_ARCHIVE_MAX_PROCESSES specifies the number of archiver background processes (ARC0 through ARC9) Oracle initially invokes. the actual number of archiver processes in use may vary subsequently based on archive workload. note: The LOG_ARCHIVE_MAX_PROCESSES parameter sets the number of ARCn processes. This parameter is automatically adjusted based on the actual situation of the database. For example:

-- Check the parameter VALUE of log_archive_max_processes SQL> show parameter log_archive_max_processes; NAME TYPE VALUE contains invalid parameter integer 4 [oracle @ bldc01 bolan] $ ps-aux | grep ora_arcWarning: bad syntax, perhaps a bogu '-'? See/usr/share/doc/procps-3.2.7/FAQoracle 20174 0.0 0.0 61184 772 pts/1 S + grep ora_arcoracle 31910 0.0 0.6 17280616 216552? Ss Mar01 12:59 ora_arc0_bolanoracle 31914 0.0 0.3 17176748? Ss Mar01 ora_arcw.bolanoracle 31918 0.0 0.6 17279920 220532? Ss Mar01 24:13 ora_arc2_bolanoracle 31922 0.0 0.7 17307772? Ss Mar01 12:44 ora_arc3_bolan