RE: Arch log files sizes

  • From: Yavor Ivanov <Yavor_Ivanov@xxxxxxxx>
  • To: "prabhu_adam@xxxxxxxxxxx" <prabhu_adam@xxxxxxxxxxx>, "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 14 Nov 2008 14:47:56 +0200

                I've seen this (even discussed it on the list)  a month or two 
ago. It was 10.2.0.4 + RAC on Solaris. The log switches ware very frequent - 
archive log file sizes were 1-5 MB, while online redo logs were 512 MB each. I 
could not determine the reason (there was no archive_lag_target set), but after 
adding some more log groups everything became normal (archive logs as big as 
95-100% of the size of online redo logs).
                Two things are sure

-          You archive logs will never be bigger than the online redo logs

-          The total size of archive logs will be always the same (the size of 
your redo information for given period), no matter the frequency of log 
stitches. If you have frequent log switches, you simply get more but smaller 
archivelogs. Of course, there may be a problem with too fast switching, but 
this does not concern your case.
So you should size your log destination depending the redo generation rate.
Regards,
Yavor Ivanov

From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of Prabhu, Krishnaswamy
Sent: Wednesday, November 12, 2008 8:33 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: Arch log files sizes

List,

We are running 10204 instances, recently the arch log destination got filled up 
100% and we noticed few arch logs files sizes are varying, the sizes are twice 
larger than the average file size, archive_lag_target is set to 0. Can anyone 
please throw more insight on this.

Thanks
Prabhu
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