| SCN:system change number and alertlogfile [message #336471] |
Sun, 27 July 2008 09:58  |
mandygrewalindia
Messages: 14
Registered: February 2008
Location: india
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Junior Member |
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hi I have following ques:
1.when i start up database, in alert log file following information is displayed:
PMON started with pid=2
DBW0 started with pid=3
LGWR started with pid=4
CKPT started with pid=5
SMON started with pid=6
RECO started with pid=7
CJQ0 started with pid=8
QMN0 started with pid=9
What does it mean?
2.I fired command alter system set log_checkpoints_to_alert=true.
I get this information:
Beginning log switch checkpoint up to RBA [0x27.2.10], SCN: 0x0000.001a7a8b can anyone explain?
3.when the database is mounted,it says database is mounted in exclusive stage.What is exclusive stage means?
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| Re: SCN:system change number and alertlogfile [message #336676 is a reply to message #336474] |
Mon, 28 July 2008 12:02  |
sunil_v_mishra
Messages: 506
Registered: March 2005
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Senior Member |
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The below mention 5 are called background process, they are mandatory background process if any one of them is killed than oracle DB will go down
[1]PMON started with pid=2
[2]DBW0 started with pid=3
[3]LGWR started with pid=4
[4]CKPT started with pid=5
[5]SMON started with pid=6
Purpose
PMON -->cleans user and server process
DBW0 -->Writes from buffer to disk and disk to buffer.
LGWR -->Write changes made to db into log file.
CKPT -->Updates SCN
SMON -->Instance Recovery.
REC0 -->Used in distributed DB
QMN0 -->Advance queueing
CJQ0 -->Co-ordinate Job queing.
Note :- Instance = Background process + Memory(SGA)
When oracle DB starts its maintain its log which is called alert log, if any error occur than that error is loged in alert log and so DBA can rectify and resolve the error.
when we issue alter system set log_checkpoints_to_alert=true.
Alert log is storing information of checkpoints
[Updated on: Mon, 28 July 2008 12:21] Report message to a moderator |
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