Wednesday, July 28, 2010

Background process

10g new background processes

With 10g many new background processes were introduced.
This note highlights those.

MMAN

Memory Manager (MMAN) coordinates the sizing of different memory components within SGA. MMAN keeps a track of sizes of components and allocates/de-allocates memory based on their usage. This process is used only when you enable Automatic Shared Memory Management.


RVWR(Recovery Writer.)
Process responsible for writing flashback logs which stores pre-image of data-blocks.
These logs can be used to flash back database to past point in time. It proves very handy specially in situation of logical data corruptions like an accidental drop/truncate of a table or commit of an unwanted transaction.


CTWR
Change Tracking Writer (CTWR) Process introduced in 10g to track changes to block to assist fast RMAN incremental backups.
MMNL
The Memory Monitor Light (MMNL) process introduced in 10g is responsible for writing out statistics buffer to disk as needed. It works with Automatic Workload Repository (AWR)



MMON
The memory monitor (MMON) process was introduced in 10g is responsible for gathering statistics for Automatic Workload Repository. This helps Oracle doing automatic problem detection and self tuning.


M000
MMON background slave (m000) processes.


RBAL
RBAL (Re-balancer) is the ASM related process that performs rebalancing of disk resources controlled by ASM.

ARBx
These processes are managed by the RBAL process and are used to do the actual rebalancing of ASM controlled disk resources. The number of ARBx processes invoked is directly influenced by the asm_power_limit parameter.

ASMB
The ASMB process is used to provide information to and from the Cluster Synchronization Services used by ASM to manage the disk resources. It is also used to update statistics and provide a heartbeat mechanism.----------------------------------------------------------------------------------------------------------
11g:

The following process are added in 11g as new background processes.

1 dbrm DB resource manager
2 dia0 Diagnosability process
3 fbda Flashback data archiver process
4 vktm Virtual Timekeeper
5 w000 Space Management Co-ordination process
6 smc0 Space Manager process

NOTE : The above six are mandatory processes.

But 11g has 56 new processes added which can be queried using

select name,description from V$bgprocess;

10g background processes:

MMAN

Memory Manager (MMAN) coordinates the sizing of different memory components within SGA. MMAN keeps a track of sizes of components and allocates/de-allocates memory based on their usage. This process is used only when you enable Automatic Shared Memory Management.


RVWR

Process responsible for writing flashback logs which stores pre-image of data-blocks.
These logs can be used to flash back database to past point in time. It proves very handy specially in situation of logical data corruptions like an accidental drop/truncate of a table or commit of an unwanted transaction.

CTWR

Change Tracking Writer (CTWR) Process introduced in 10g to track changes to block to assist fast RMAN incremental backups.

MMNL

The Memory Monitor Light (MMNL) process introduced in 10g is responsible for writing out statistics buffer to disk as needed. It works with Automatic Workload Repository (AWR)

MMON

The memory monitor (MMON) process was introduced in 10g is responsible for gathering statistics for Automatic Workload Repository. This helps Oracle doing automatic problem detection and self tuning.

M000

MMON background slave (m000) processes.

RBAL

RBAL (Re-balancer) is the ASM related process that performs rebalancing of disk resources controlled by ASM.

ARBx

These processes are managed by the RBAL process and are used to do the actual rebalancing of ASM controlled disk resources. The number of ARBx processes invoked is directly influenced by the asm_power_limit parameter.

ASMB

The ASMB process is used to provide information to and from the Cluster Synchronization Services used by ASM to manage the disk resources. It is also used to update statistics and provide a heartbeat mechanism.


 use link to see how architecture work
http://www.youtube.com/watch?v=meWIB3yt96U











Wednesday, July 7, 2010

Errors

GETTING THIS ERROR
ORA-01157:cannot identify/lock data file 1 - see DBWR trace file
ORA-01110:data file 1: 'D:\ORACLE\PRODUCT\10.2.0\ORADATA\HRMSD91\SYSTEM01.DBF'

__________________________________________________________________________________


ERROR due to flash recovery area  and solution for it :



SQL> conn sys as sysdba
Enter password:
Connected to an idle instance.
SQL> startup
ORACLE instance started.

Total System Global Area  608174080 bytes
Fixed Size                  1292036 bytes
Variable Size             167774460 bytes
Database Buffers          436207616 bytes
Redo Buffers                2899968 bytes
Database mounted.
ORA-16038: log 3 sequence# 430 cannot be archived
ORA-19809: limit exceeded for recovery files
ORA-00312: online log 3 thread 1:
'D:\ORACLE\PRODUCT\10.2.0\ORADATA\HRM\REDO03.LOG'


SQL> alter system switch logfile
  2  ;
alter system switch logfile
*
ERROR at line 1:
ORA-01109: database not open


SQL> archive log list
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     430
Next log sequence to archive   430
Current log sequence           432

SQL> show parameter db_recovery_file_dest

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest                string      D:\oracle\product\10.2.0\flash
                                                 _recovery_area
db_recovery_file_dest_size           big integer 3G
SQL> exit
Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - Pr
oduction
With the Partitioning, OLAP and Data Mining options

C:\Documents and Settings\Sundaresh>set oracle_sid=hrm

C:\Documents and Settings\Sundaresh>sqlplus

SQL*Plus: Release 10.2.0.3.0 - Production on Tue Sep 28 12:00:44 2010

Copyright (c) 1982, 2006, Oracle.  All Rights Reserved.

Enter user-name: sys as sysdba
Enter password:

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - Production
With the Partitioning, OLAP and Data Mining options

SQL> select name from v$database;

NAME
---------
HRM


SQL> alter system set db_recovery_file_dest_size=2G scope=both;

System altered.

SQL> ALTER DATABASE OPEN;
ALTER DATABASE OPEN
*
ERROR at line 1:
ORA-16014: log 3 sequence# 430 not archived, no available destinations
ORA-00312: online log 3 thread 1:
'D:\ORACLE\PRODUCT\10.2.0\ORADATA\HRM\REDO03.LOG'


SQL> alter system set db_recovery_file_dest_size=5g
  2  ;

System altered.

SQL> alter database open resetlogs;
alter database open resetlogs
*
ERROR at line 1:
ORA-01139: RESETLOGS option only valid after an incomplete database recovery


SQL> alter database open ;

Database altered.