On 01/30/2004 01:24:26 PM, A Joshi wrote:
Hi,
  In view v$log there is a column status. This changes from current
(if the redo log is in use) to atcive then to inactive. Documentation
says  :


ACTIVE: The log is active but is not the current log. It is needed for
crash recovery. It may be in use for block recovery. It might or might
not be archived.


INACTIVE: The log is no longer needed for instance recovery. It may be
in use for media recovery. It might or might not be archived.


So if it is in 'ACTIVE' status : it means it is needed for
crash/instance recovery? So what does it mean? That changes in this
log are still not written to data files? What else? Is this related to
delayed block cleanout etc or no connection?


What factor affects  how long it will be in ACTIVE state before going
to INACTIVE? What can be changed to control how long it takes. Any
trade off?

Any detailed explanation on this will be greatly appreciated. You can
mail me direct or to the list. Thank you.

Status of active means that log has been switched, but not all of the changes are written to the disk. It is, essentially, saying that DBWR
has some more work to do to catch up. The only log that is open by the
instance is the one marked "CURRENT". Here is an example:
SQL> select group#,status from v$log;


   GROUP# STATUS
---------- ----------------
        1 CURRENT
        2 INACTIVE
        3 INACTIVE

SQL> alter system switch logfile;

System altered.

SQL> select group#,status from v$log;

   GROUP# STATUS
---------- ----------------
        1 ACTIVE
        2 CURRENT
        3 INACTIVE

So, after the checkpoint, the CKPT has updated log file headers, corresponding markers and termination records are written to the file,
data file headers have been updated and so has been the control file.
DBWR still has some work to do because there are still unwritten blocks modified by transactions whose log records are in the "ACTIVE"
file. DBWR will take its time to write them down.
The only log file open by the instance is redo02:


[EMAIL PROTECTED] root]# fuser /data/db/OraHome1/oradata/compldb/*.log
/data/db/OraHome1/oradata/compldb/redo02.log:  6019
[EMAIL PROTECTED] root]#

After another checkpoint, everyhing is back to normal:

SQL> alter system checkpoint
 2  /

System altered.

SQL> select group#,status from v$log;

   GROUP# STATUS
---------- ----------------
        1 INACTIVE
        2 CURRENT
        3 INACTIVE

--
Please see the official ORACLE-L FAQ: http://www.orafaq.net
--
Author: Mladen Gogala
 INET: [EMAIL PROTECTED]

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).

Reply via email to