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Startup Database At Restricted Mode

23:38 Admin 1 comment

You can also start the database in restricted mode. Restricted mode will only allow users with special privileges (we will discuss user privileges in a later chapter) to access the database (typically DBA’s), even though the database is technically open. We use the startup restrict command to open the database in restricted mode as seen in this example.

SQL> startup restrict

You can take the database in and out of restricted mode with the alter database command as seen in this example:

SQL> alter system enable restricted session;

-- Take the database out of restricted session mode.

SQL> alter system disable restricted session

Related Post:

Startup Oracle Database at Open Stage

21:14 Admin No comments

When Oracle opens the database, it accesses all of the datafiles associated with the database. Once it has accessed the database datafiles, Oracle makes sure that all of the database datafiles are consistent.Oracle opens the online datafiles and online redo log files. If a tablespace was offline when the database was previously shut down, the tablespace and its corresponding datafiles will still be offline when you reopen the database.

To open the database, you can just use the startup command

SQL> startup mount

If the database is mounted, you can open it with the alter database open command

SQL> alter database open

Startup Oracle Database at Mount Stage

20:40 Admin No comments

You can start an instance and mount a database without opening it, allowing you to perform specific maintenance operations. When the startup command enters the mount stage, it opens and reads the control file. The control file is a binary file that tracks important database information, such as the location of the database datafiles.

In the mount stage, Oracle determines the location of the datafiles, but does not yet open them. Once the datafile locations have been identified, the database is ready to be opened.For example, the database must be mounted but not open during the following tasks

Enabling and disabling redo log archiving options
Performing full database recovery

The following command starts an instance and mounts the database

SQL> startup mount

If you have already started the database instance with the startup nomount command, you might change it from the nomount to mount startup stage using the alter database command:

SQL> alter database mount

Related Post :-

Startup Oracle Database at NoMount Stage

19:45 Admin No comments

Normal database operation means that an instance is started and the database is mounted and open. This mode allows any valid user to connect to the database and perform data access operations. The following command starts an instance, reads the initialization parameters from the default location, and then mounts and opens the database. (You can optionally specify a PFILE clause.)

STARTUP

You can start an instance without mounting a database. Typically, you do so only during database creation. Use the STARTUP command with the NOMOUNT clause:

STARTUP NOMOUNT

The instance starts, but does not mount the control file or open the database. This status of the instance enables the following tasks:

1. To create a new database or

2. A new control file or

3. To recover control file.

When you start an instance at nomount stage it reads initialization parameter file determine the values of initialization parameters. Then, it allocates an SGA, which is a shared area of memory used for database information, and start background processes. At this point, no database is associated with these memory structures and processes.

Related Post :-

Starting Up Oracle Database

19:09 Admin No comments

One of the most common jobs of the database administrator is to startup or shutdown the Oracle database. To start an instance, the database must read the initialization parameters or SPFILE. When you issue the SQL*Plus STARTUP command, the database attempts to read the initialization parameters from an SPFILE in a platform-specific default location. If it finds no SPFILE, it searches for a text initialization parameter file.

In the platform-specific default location, Oracle Database locates your initialization parameter file by examining filenames in the following order:

spfileSID.ora
spfile.ora
initSID.ora

You start the Oracle database with the startup command. You must first be logged into an account that has sysdba or sysoper privileges. DBA connecting to the database and starting the instance:

[oracle10@localhost ~]$ export_SID=dbn

[oracle10@localhost ~]$ aqlplus "/as sysdba"

SQL*Plus: Release 10.2.0.1.0 - Production on Wed Nov 9 14:18:33 2011

Connected to an idle instance

SQL> startup

ORACLE instance started.

Total System Global Area 314572800 bytes

Fixed Size 1219160 bytes

Variable Size 96470440 bytes

Database Buffers 213909504 bytes

Redo Buffers 2973696 bytes

Database mounted.

Database opened.

SQL>

We set the ORACLE_SID to the name of the database and we log into SQL*Plus using the “sys as sysdba” login. This gives us the privileges we need to be able to startup the database. Finally, after we enter our password, we issue the startup command to startup the database. Oracle displays its progress as it opens the database, and then returns us to the SQL*Plus prompt once the startup has been completed. When Oracle is trying to open your database, it goes through three distinct stages.These stages are