Mandatory processes in Oracle DBA

 

Mandatory processes

   

The SMON performs the recovery when a failed instance starts up again.  

Emoked ………… whenever any commit transaction found in redo log files

………… whenever any T_x updated db files before the server down then SMON rolls back the contents from the undo log file. [craoh recovery]

 

 

• The PMON performs a process when a user process fails.
• It will rollback uncommitted transactions
• It will unlock the resources [tables] if any locked for a longer time.  

 

 

The DBWR writes the direct buffers present in the database buffer cache to respective files. When a checkpoint & issue index files db files undo files

• Every 3 seconds time-out
• When a log switch occurs
• When dirty-blocks are becoming LRU blocks
• When dirty-blocks reach a threshold value.
• When the database shuts down.

 

The writer is activated under the following conditions.

The log writer process writes data from the redo log buffers to the redo log files.

1. Every 3 seconds
2. When a t_x is committed or rolled back.

• When the redo log buffer is 1/3 full

   

The checkpoint process signals the synchronization of all database files with the checkpoint information

The CKPT process is invoked under the following it ensures data consistency and farter database recovery in case of a crash.

1. When a log switch is done
2. For all occasions [before in fact] the DBWR invokes.
3. Whenever an event like “offline” occurs.

whenever the state of redo log files is ACTIVE

Then the DBWR & ARCH files invoke.

Then the state is called ‘PAUSE’ state The solution is

The archive files are not cyclic and help in crash recovery

whenever the existing 2 redo log files are in the state of ‘Active’

1. Adding 1 more redo log file the size of existing redo log files

 

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Ermine log 

Installation: operating system can be installed

Restoring: database can be restored

Recovery:  archive files, we can be recovered the data ORACLE stores the data

   

Logically in tablespace & Physically in data files.

   

[done transitions] already involved but not get written  to their respected files

   

WEBr applications dba12

Login: raj6x 71A

[dba12 raj6x71A] $ ls  -a

.bash-profile

[dba12  raj6x71A]$ vi .bash-profile

~

~

~

~

Export ORACLE –SID = rajpar

Export ORACLE _HOME=/oraeng/app/oracle/product/10.2.0

Export PATH=$ORACLE_HOME/bin:$PATH:

~

~

~

~

: wq

[dba12 raj6x71A]$ . .bash – profile

[dba12 raj6x 71A] $ echo $ORACLE_SID rajpan

[dba12 raj6x71A] $ echo $ ORACLE_HOME/oraeng/app/oracle/product/10.2.0

[dba12 raj6x71A]$ echo $PATH

……………..

…………….

dba12 raj671a/oraeng/app/oracle/product/ 10.2.0/bim::..

……………. [dba12 raj6x71A]$C

[dba12 raj6x 71A] $cd     $ORACLE _ HOME

[dba12 10.2.0] $ ls

……………               …………..                                ……………….           ……………….

dbs      …………..                                …………..                                ……………….           ……………….

……………               …………..                                ……………….           ………………..

……………               …………..                                ……………….           ………………..

[dba12 10.2.0] $ cd dbs

[dba12 dbs] $ ls

……………..             ………………            ………………            ……………….           ……………….

……………..             ………………            ………………            ……………….           ……………….

……………..             ………………            ………………            ……………….           ……………….

……………..             ………………            ………………            ………………            ………………..

……………..             ………………            ………………            ……………….           …………………

init.ora                  ……………..             ………………            ……………….           …………………

……………..             ……………..             ………………            ……………….           …………………

[dba12 dbs] $ cp init.ora                init$ORACLE_SID.ora

[dba12 dbs] $ ls

…………..                                ……………..             ……………..             …………….              ………………

…………..                .               ……………..             ……………..             …………….              ………………

…………..                                ……………...           ………………            ……………..             ………………

……………               ………………            ……………..             ………………            ……………….

…………..                                ……………..             ……………..             initrajpar.ora      ……………….

…………..                                ……………….           ……………….           ………………..         …………………

……………               ………………            ………………..         ………………            …………………

……………               ……………..             ………………            ……………….           ………………..

……………               ………………            ………………..         ……………….           …………………

……………               ………………            ……………….           ……………….           …………………

…………..                                ……………….           ……………….           ………………..         …………………

……………               ………………            ………………..         ………………            …………………

……………               ……………..             ………………            ……………….           ………………..

……………               ………………            ………………..         ……………….           …………………

……………               ………………            ……………….           ……………….           …………………                         ……………   

……………….                ………………..         ………………            ………………….

[dba12 dbs] $ c

[dba12 dbs]$ vi initrajpar.ora

#

#

#

#

#

#

#

db_name=rajpal

instance_name=rajpar

..

..

~

~

…

~

~

#

Control_files=/disk3/oradata/pal/cont.ctl

user-dump-dest=/disk3/oradata/pal/cdump

core_dump_dest=/disk3/oradata/pal/cdump

background_dump_dest=disk3/oradata/pal/bdump  

~

~

~

~

#

#

:wq

[dba12 dbs] $C

[dba12 dbs] $ cd

[dba12 ~] $ cd / disk3

[dba12 disk3 ] $ cd / oradata

[dba12 oradata] $ mkdir

pal [dba12 oradata] $ ls

............                                …………                   ……………               ……………               …………….  

            …………..                                ………….

............                                …………                   ……………               ……………               …………….     

         …………..                                …………..

............                                …………                   ……………               pal                          …………….         

     …………..                                ………….

[dba12 oradata] $ cd pal

[dba12 pal] $ ls

[dba12 pal] $ mkdir udump cdump bdump

[dba12 pal] $ ls

bdump cdump udump

[dba12 pal] $ cd

[dba12 ~] $ sqlplus “/as sysdba”

SQL > startup nomount

Total system global area

Fixed size

variable size

database buffers

redo buffers

SQL > ed cr8db

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