Remote DBA team - Oracle database startup and shutdown processes. Detail and explaination for OCP exam preparation of 1z0-031,1z0-041,1z0-051 exams. Learn by presentation series brought by www.dbametrix.com.

1. DBAMETRIX Solutions
Present
Oracle Startup & Shutdown
Process

2. Oracle DBA Learn by Presentation series
• Oracle DBA learning by presentation offered by
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• This all presentations have been prepared by Gitesh P
Trivedi.
• Gitesh Trivedi has 14 years working experience in DBA
field and as expert consultant faculty.
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3. In this session we get detail information for
following topics
• Which type of shutdown options available
• Which type of startup options available
• How Oracle database shutdown
• How SGA de-allocates from memory region
• How Oracle protects committed and un-committed data
• How Oracle performs normal startup
• How Oracle checks datafiles and controlfiles using
internal check-up
• How Oracle enables & performs recovery process
• What are the internal processes

4. Shutdown Process
• Following options are available in Oracle
• Shutdown normal
• Shutdown transactional
• Shutdown immediate
• Shutdown abort

5. Shutdown normal
• Using command “shutdown;” or “shutdown normal;”.
• Default option is normal.
• Oracle triggers checkpoint process and all dirty buffers
flush in to disk.
• Checkpoint writes stop system change number (STOP
SCN) in to controlfile and updates all respective datafile
header.
• Oracle drops all temporary segments from temp
tablespaces.
• Oracle closes all datafiles and online redologfiles.
• Oracle de-allocates SGA from memory region of
operating system.

6. Shutdown Normal
New connection not
Existing Session can allow
do work
Buffer Log
Buff Shared Pool C
Cache er on
St
r
Sort Ext Pool SGA
Control
File
Stop: SCN Dbwr
Log Writer
SCN:
Datafiles
Log Log
File File
Group- Group
1 -2

7. While executing Shutdown Normal
• Existing session can perform work. Once those logout after
that don’t get connection.
• No new session allows.
• After all sessions logout then Oracle starts shutdown process.
• Checkpoint occurs, dirty buffers flush in to disk.
• LGWR flushes data from Log Buffer to Online redo log files.
• Stop system change number generates and stores in
controlfile (Stop: SCN) as well as all datafiles (Current: SCN).
• If shutdown event trigger exists then fires.
• Temporary segments drop from temporary tablespace.
• Oracle closes all datafiles, redo logs and controlfiles.
• Oracle de-allocates shared global area from memory region of
Operating system.

8. Practically we take example of “shutdown”
normal command as follows.

9. Shutdown Transactional
New connection not
Existing Session can do allow
work, End of transaction
session ended
Buffer Log
Buff Shared Pool C
Cache er on
St
r
Sort Ext Pool SGA
Control
File
Stop: SCN Dbwr
Log Writer
SCN:
Datafiles
Log Log
File File
Group- Group
1 -2

10. While executing Shutdown Transactional
• Existing session can perform work. Once transaction to be
ended it becomes kicked off from database. If logout then also
doesn’t get connection.
• No new session allows.
• After all sessions logout then Oracle starts shutdown process.
• Checkpoint occurs, dirty buffers flush in to disk.
• LGWR flushes data from Log Buffer to Online redo log files.
• Stop system change number generates and stores in
controlfile (Stop: SCN) as well as all datafiles (Current: SCN).
• If shutdown event trigger exists then fires.
• Temporary segments drop from temporary tablespace.
• Oracle closes all datafiles, redo logs and controlfiles.
• Oracle de-allocates shared global area from memory region of
Operating system.

11. Practically we can take example of
“shutdown transactional” as follows

12. Shutdown Immediate
New connection not
allow
ALL Existing Session
disconnect immediately
Buffer Log
Buff Shared Pool C
Cache er on
St
r
Sort Ext Pool SGA
Control
File
Stop: SCN
Log Writer
Dbwr
SCN:
Datafiles
Log Log
File File
Group- Group
1 -2

13. While executing Shutdown Immediate
• Existing ALL sessions are kicked off from database. They
loose connection from database.
• No new session allows.
• User will lose all uncommitted transaction data. Immediately
Oracle starts shutdown process.
• Checkpoint occurs, dirty buffers flush in to disk.
• LGWR flushes data from Log Buffer to Online redo log files.
• Stop system change number generates and stores in
controlfile (Stop: SCN) as well as all datafiles (Current: SCN).
• If shutdown event trigger exists then fires.
• Temporary segments drop from temporary tablespace.
• Oracle closes all datafiles, redo logs and controlfiles.
• Oracle de-allocates shared global area from memory region of
Operating system.

14. Practically we can take example of
“shutdown immediate” as follows

15. Shutdown abort
New connection not
allow
ALL Existing Session
disconnect immediately
Buffer Log
Buff Shared Pool C
Cache er on
St
r
Sort Ext Pool SGA
Control
File
Stop: SCN
Log Writer Dbwr
SCN:
Datafiles
Log Log
File File
Group- Group
1 -2
Shutdown
SGA/Instance

16. While executing Shutdown ABORT
• Existing ALL sessions are kicked off from database. They loose
connection from database.
• No new session allows.
• User will lose all uncommitted transaction data. Immediately Oracle
starts shutdown process.
• NO Checkpoint occurs & NO dirty buffers flush in to disk.
• NO LGWR flushes data from Log Buffer to Online redo log files.
• There is no STOP SCN generated and not Controlfile, datafile
header updated.
• No shutdown event trigger even if exists.
• No Temporary segments drop from temporary tablespace.
• Oracle closes only Instance (SGA and background processes).
• Database will be in inconsistence mode.

17. Problem occurs during shutdown process
• Oracle updates alert.log in every shutdown options.
• If any error occurs Oracle logs in to alert.log.
• During “shutdown immediate” option, Oracle may takes
time for shutting down database due to rollback pending
transaction.
• Without “abort” option, Database is consistence mode in
all other shutting down options. We can take cold
backup.
• In “shutdown abort” option, database is in inconsistence
mode, we can’t take cold backup.

18. Practically we can take example of
“shutdown abort” as follows

19. Physical structure of Oracle database
• Parameter file (init.ora & spfile)
• Password file
• Control files
• Online redo log files
• Datafiles
• Trace files including alert.log
• If sys user’s audit enables then audit files

20. Startup Process
• Step by step startup command
• Startup nomount ( only instance started)
• Startup mount (control file open and check)
• Startup open ( datafiles and redo log files open and
check)
• Startup force ( forcibly instance start and instance
recovery perform)
• All commands are available after each step
• Oracle logs all details and error in alert.log file during
startup command execution

21. Startup nomount
• Oracle reads parameter file and populates instance.
• Before startup instance Oracle also checks password file
and match it.
• Oracle also reads location and name of controlfile from
parameter file (init.ora or spfile).
• Shared Global Area and background processes are
starting.
• After finishing command execution successfully, Oracle
prompts message “instance started”.
• This command is useful for new database creation and
controlfile recreation.

22. Startup nomount Parameter
file
Buffer Log
Buff Shared Pool C
Cache er on
St
r
Sort Ext Pool SGA Pmon
Dbwr
Smon

23. Startup mount
• After instance starts next step is mount.
• In mount stage Oracle opens all controlfiles from each
location and read contains. It also checks STOP SCN
from controlfile.
• If controlfile is missing or corrupt, Oracle gives error in
mount stage only.
• If any datafile or online redo log file is missing there is no
error will be generated.
• If we started instance using “startup nomount” then we
can mount database using “alter database mount;”
command.

24. Startup mount Parameter
file
Buffer Log
Buff Shared Pool C
Cache er on
St
Control r
File Sort Ext Pool SGA Pmon
Stop: SCN
Dbwr
Smon

25. Practically we can take example of “startup”
step by step as follows

26. Startup open
• After mounting database, Oracle opens all datafiles and
online redo log files.
• Oracle matches STOP SCN of controlfile to each and every
datafile (from header of datafile).
• If Oracle finds any mismatch of this number due to instance
crash or “shutdown abort” then it performs instance recovery.
• If Oracle finds any mismatch of this number due to not above
circumstances then asks for media recovery.
• Alternate we can use “alter database open” command after
mounting database with “startup mount;”.
• If startup event trigger exists then fires after open database.

27. Startup open Parameter
file
Buffer Log
Buff Shared Pool C
Cache er on
St
Control r
File Sort Ext Pool SGA Pmon
Stop: SCN
Dbwr
Smon
SCN:
Datafiles
Log Log
File File
Group- Group
1 -2

28. Practically we can take example of normal
“startup” as follows

29. When Oracle performs recovery?
• When Instance crashed.
• When issued “shutdown abort”.
• When mismatch found of SCN of controlfile and any of
datafile’s header.
• During instance recovery Oracle performs roll-forward
and roll-backward scenario.
• If Oracle finds any of new datafile or older datafile means
new Stop: SCN or older Stop: SCN then asks for media
recovery.
• After starting database Stop SCN becomes infinitive in
controlfile.

30. DBAMETRIX Solutions
Present
Oracle Startup and Shutdown Process
Prepared By: Gitesh P Trivedi
gitesh@dbametrix.com
http://www.dbametrix.com