Updation of controlfile
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Thread: Updation of controlfile

  1. #1
    Join Date
    Sep 2002
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    Hi,
    Which process is responsible for updating CONTROL FILE abt
    the datafile path, tablespace name and archives info.

    I know that SCN is updated by ckpt. But have doubt for the above info

    Regards
    rakesh

  2. #2
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    Originally posted by bang_dba
    Hi,
    Which process is responsible for updating CONTROL FILE abt
    the datafile path, tablespace name
    It's server process I guess


    and archives info.

    no idea about this

    -nagarjuna

  3. #3
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    I don't think server process is the one who does this....coz when some of the modifications what we do at the mount phase is also reflected in the control file; like when we change the name of the system datafile in the mount phase it is automatically reflected in the control file, during which there is no server proess started.....

    I guess Oracle kerner internally writes to the controlfile abt the physical changes.....i am not sure abt this...

    Can some experts put light on this ?

    sonia

  4. #4
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    Originally posted by Sonia
    .... in the mount phase it is automatically reflected in the control file, during which there is no server proess started.....
    What makes you think there is no server process started when database is mounted? In mount phase, the instance is allready started and functioning - SGA is formed, background processes started, it is only the database files that are not opened yet.

    If you check the process scheme (Figure 8-2 in Concepts manual) http://download-west.oracle.com/docs...rocs.htm#18128, it clearly indicates which server processes are responsible for updating control file information: LGWR, CKPT and ARCn. There might be some othere process that interacts with controlfiles that are not indicated on that picture, but those three are the main contributors for controlfile information.
    Jurij Modic
    ASCII a stupid question, get a stupid ANSI
    24 hours in a day .... 24 beer in a case .... coincidence?

  5. #5
    Join Date
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    Right... its the ARCn process which does the job. The moment DB is mounted, SGA is formed,Background process starts, LGWR,ARCn starts.

    Thanks
    PNRDBA

  6. #6
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    Originally posted by jmodic
    What makes you think there is no server process started when database is mounted? In mount phase, the instance is allready started and functioning - SGA is formed, background processes started, it is only the database files that are not opened yet.

    If you check the process scheme (Figure 8-2 in Concepts manual) http://download-west.oracle.com/docs...rocs.htm#18128, it clearly indicates which server processes are responsible for updating control file information: LGWR, CKPT and ARCn. There might be some othere process that interacts with controlfiles that are not indicated on that picture, but those three are the main contributors for controlfile information.

    CKPT => updates checkpoint
    LGWR => updates about log switches and log sequence numbers
    ARCn => writes about the archivelogs

    Then, who else updates about the datafile path and their name??? I think it should the be the server process that invokes the session.

    Is there anyway to find out which process acts at a particular time and the name of the file???
    -nagarjuna

  7. #7
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    Nagarjuna,

    I agree with you that it is not clear which process writes to controlfiles when you change some datafile or logfile names - that's why I said
    There might be some othere process that interact with controlfiles that are not indicated on that picture
    . However I'm sure of one thing: It is certainly not session's server process. Those processes never write anything to the database, all of their I/O activities are READs and READs only. I'm also cetain it is not ARCn processes (because there might not be any of them in the instance). I would not rule out neither CKPT nor LGWR to be responsible for this job, as well as maybe DBWR. I'm also positive SMON and PMON have nothing to do with that.
    Jurij Modic
    ASCII a stupid question, get a stupid ANSI
    24 hours in a day .... 24 beer in a case .... coincidence?

  8. #8
    Join Date
    Feb 2002
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    Jmodic,
    yeh....a server process gets started as soon as you connect...

    sql>connect / as sysdba
    sql>startup mount

    Is this process also responsible for initializing the SGA and starting other background processes....

    And one more thing............is the serverprocess also considered as a background process ?
    or is it called as a foreground process ?

    regards
    sonia

  9. #9
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    Originally posted by Sonia
    Jmodic,
    yeh....a server process gets started as soon as you connect...

    sql>connect / as sysdba
    sql>startup mount

    Is this process also responsible for initializing the SGA and starting other background processes....

    And one more thing............is the serverprocess also considered as a background process ?
    or is it called as a foreground process ?

    regards
    sonia
    We have 2 types of processes. Oracle process and user process. Oracle process is spawned at the server. Oracle processes further devided into two. 1. Server process and 2. Back ground process. Server processes are spawned when an user connects to database. Back ground processes are spawned when Oracle starts. Back ground processes are LGWR, DBWn, ARCn, CKPT etc. User processes can be spawned at either server or user's terminal depending on the configuration. I learnt all these things exactly 310 days when I attened my 1st ever Oracle class
    -nagarjuna

  10. #10
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    Originally posted by Sonia
    Jmodic,
    yeh....a server process gets started as soon as you connect...

    sql>connect / as sysdba
    sql>startup mount

    Is this process also responsible for initializing the SGA and starting other background processes....
    Yes, I would say so.
    And one more thing............is the serverprocess also considered as a background process ?
    or is it called as a foreground process ?
    [/B]
    No, server process (a process that is opened by RDBMS on behalf of user's application process) is never considered as "background process" in the context of Oracle's process terminology. AFAIK Oracle documentation allways mention only two tipes of processes that are handled by RDBMS on the server side: "background processes" (PMON, SMON, DBWR, LGWR, ......) and "server processes" (processes that handle user requests against the database). I don't remember coming across the term "foreground process" in this context.
    Jurij Modic
    ASCII a stupid question, get a stupid ANSI
    24 hours in a day .... 24 beer in a case .... coincidence?

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