Oracle Control files

In Oracle, the control file is the file used when the database is mounted, the control file is lost or corrupted, and the instance crashes, where the parameter file records the location of the control file;

After the instance starts to Nomount, if the Db_names parameter is consistent with the database name recorded in the control file, mount is not allowed, otherwise it will be error;

To boot to mount, the instance will determine the location and number of control files and the consistency;

The control file records the structure and behavior of the database instance, including database data file, redo log file, database name, database creation information, tablespace information, data file status, log file information, backup information, checkpoint information, etc.

A database must have at least one control file, up to 8, typically set to 2, placed under different paths.

In managing the control files, the DBA needs to focus on the following issues:

1, the number of control files

2, control file version problem

3, Control file backup (cold, hot standby)

4, control file size control within 100M

The following are views about Oracle and control files:

V$database records the database information read in the control file

V$controlfile Record control File details

V$controlfile_record_sectiong records the contents of a control file record

V$parameter record the control file parameters corresponding to the Control_files parameter

For example, we can view the location of the control file in V$controlfile:

Sql> select name from V$controlfile;

NAME

-----------------------------------------------

/u01/oracle/oradata/wyzc/control01.ctl

/data1/oracle/oradata/control02.ctl

/data2/oracle/oradata/control03.ctl

If we want to know what information is recorded in the control file, we can use the V$controlfile_record_sectiong

Sql> Select type from v$controlfile_record_section;

TYPE

----------------------------

DATABASE

CKPT PROGRESS

REDO THREAD

REDO LOG

DataFile

FILENAME

Tablespace

Temporary FILENAME

RMAN CONFIGURATION

LOG history

OFFLINE RANGE

Archived LOG

BACKUP SET

BACKUP PIECE

BACKUP datafile

BACKUP Redolog

DataFile COPY

BACKUP corruption

COPY corruption

DELETED OBJECT

PROXY COPY

BACKUP SPFILE

DATABASE incarnation

FLASHBACK LOG

RECOVERY DESTINATION

INSTANCE SPACE Reservation

Removable RECOVERY FILES

RMAN STATUS

THREAD INSTANCE NAME MAPPING

MTTR

DataFile History

STANDBY DATABASE MATRIX

Guaranteed RESTORE Point

RESTORE Point

DATABASE BLOCK corruption

ACM operation

FOREIGN archived LOG

PNs rows selected.

In the Oracle 11g R2 release, the control files recorded a total of 37 content, as above.

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Oracle Control files