Oracle Physical Storage Architecture

Oracle Physical Storage Architecture

The database is actually composed of a bunch of physical files, there are 4 main:
1. Control files
2. Data file (Date files)
3. Redo log file (Redolog)

1. Control files

The control file is the root file of the database where he locates the database files
There are:

• The database's name, DBID, and database unique identifier.
• Database Creation Date
• Data files, redo logs, archive log file information.
• Tablespace's information.
• Rman Backup

Control files He has two purposes.

1. Contains information about where data files,redo files are stored. So there is no control file, the database is not able to mount, because he can not locate the basic data files.
2. Some of the metadata that is allowed in the database is recorded inside, such as information about the checkpoint.

Query control File Information

show parameter control_files;select name from v$controlfile;

Specify the control file

In fact, it is specified in the Pfile, DBCA when the database is created.

2. Data files

The data in the database is actually stored in the data file. He generally has a close relationship with TABLESAPCE, a tablespace can be composed of several data files, but a data file can only be used for a tablespace. Tablespace is a logical concept. The data file is a physical concept.

Querying data files

selectfrom v$datafile;

Status of the data file

Online,offline,system, mainly the first 2, online and offline state, offline state, the data will not be able to access.
For example, a data file offline can be executed

‘/u01/app/oracle/oradata/test58/zabbix.dbf‘ offline;

Note, however, that the data file can be offline only if the DB is turned on in archive mode, or an error will be

ORA-01145offline immediate disallowed unless media recovery enabled

Viewing error messages

011450114500000"offline immediate disallowed unless media recovery enabled"... OFFLINE IMMEDIATE or ALTER DATABASE DATAFILE//         ...ifin ARCHIVELOG mode.// *Action:Take tablespace offline normally or shutdown abort. Reconsider your//         if you were archiving your logs.

What is the archive mode, please see the redo log inside the relevant operation.

3. Redo Log Files

Redo log is actually a very important thing, redo is usually specified when building a library.

selectfrom v$log

Turn on archive mode

1. See if it is in archive mode:

loglistlog mode          No Archive ModeAutomatic archival         DisabledArchive destination        /u01/app/oracle/product/11.2.0log sequence     36log sequence           38

2. Backing Up the database

3. Edit Pfile

LOG_ARCHIVE_DEST="/u01/app/oracle/oradata/test58/archive"

Make sure you have this directory.

4. Start the database, but do not open
Startup Mount

5. Turn on archive mode and open the database

alter database ARCHIVELOG;alter database open;

6. View status

loglog mode          Archive ModeAutomatic archival         EnabledArchive destination        log sequence     36Nextlogto archive   38log sequence           38

Oracle Physical Storage Architecture