Size archive log different with online redo log

[Former Member]

Dear Experts,

I had a problem with archive redo log size. I saw the size between archive redo log and online redo log is different.

The online redo log on path /oracle/SID/origlogA/log_g17m1.dbf , the size is 280MB, but on archive log the size just 130MB.

Why the size different? How to change the archive redo log?

We are running with Oracle 11.2.0.4.

Please aid me to solve this issue.

Thanks

Edy

[janos_mucsi-besze]

Dear Edy,

It is really not an issue. Preemtive redolog switch is the name of this feature, which is described throughtly in the below note:

1627481 - Preemptive redolog switches in Oracle 11.2

Just for your reference I attach the archived redolog sizes one of my testsystems:

Also I must draw your attention to some facts here:

- each of my online redologs have the size in bytes, 52428800

- the ones with some kbyte sizes were created while is executed 'alter system switch logfile' and there was almost nothing going on or executed on the database

Regards,

János

[ashish_vikas]

please read :

Note 998675 - Archive log of smaller size than the original redo log

best regards

ashish

[Former Member]

It is not an issue, archive log's size can be equal to you redolog size as archiving process happens from online redologs.

Regards,

Nick Loy

[Former Member]

Hi Nick,

Thanks for your reply

But in our system, the size online redo log and archive is not equal.

Size online redo log  = 280MB

Archive log               = 130MB

Why this happen? and how to make it's equal?

Thanks

Edy

[Former Member]

Hi,

LGWR archives the online transactions and writes in an archive log whenever there is a commit happened for the online transactions (of redolog in use).

Is this size mismatch happening for all the archive logs or for one which you are looking at?

Regards,

Nick Loy

[Former Member]

Hi,

Yes, all of the size archive logs mismatch with online redolog.

I tried dump the trace file using command "alter database backup control file to trace file" and here is the result:

STARTUP NOMOUNT
CREATE CONTROLFILE REUSE DATABASE "SID" NORESETLOGS  ARCHIVELOG
    MAXLOGFILES 255
    MAXLOGMEMBERS 3
    MAXDATAFILES 508
    MAXINSTANCES 50
    MAXLOGHISTORY 46720
LOGFILE
  GROUP 5 (
    '/oracle/SID/origlogA/log_g15m1.dbf',
    '/oracle/SID/mirrlogA/log_g15m2.dbf'
  ) SIZE 280M BLOCKSIZE 512,
  GROUP 6 (
    '/oracle/SID/origlogB/log_g16m1.dbf',
    '/oracle/SID/mirrlogB/log_g16m2.dbf'
  ) SIZE 280M BLOCKSIZE 512,
  GROUP 7 (
    '/oracle/SID/origlogA/log_g17m1.dbf',
    '/oracle/SID/mirrlogA/log_g17m2.dbf'
  ) SIZE 280M BLOCKSIZE 512,
  GROUP 8 (
    '/oracle/SID/origlogB/log_g18m1.dbf',
    '/oracle/SID/mirrlogB/log_g18m2.dbf'
  ) SIZE 280M BLOCKSIZE 512
-- STANDBY LOGFILE
DATAFILE

Output ommited

Thanks

Edy

[Reagan]

But in our system, the size online redo log and archive is not equal.

This is not an issue.

The log switch can happen as designed and not necessarily when it reaches the size of the online redolog.

Regards

RB