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archive log file size [message #120718] Mon, 23 May 2005 04:21 Go to next message
patrick
Messages: 83
Registered: December 2000
Member
I got archivelogging working. (see the other post I made)

This is a completely new question to the topic so that's why i made a new topic.

The archive log files are 100 mb in size. This is because the redo tabel is 100 mb i quess.

I have the idea that i lose data for a long time with a crash so i wanted to know if it is possible to make the log files 1 mb in size. So that allmost every change is written to archive log right away.

This is probebly something like max size or so?

Patrick
Re: archive log file size [message #120755 is a reply to message #120718] Mon, 23 May 2005 09:51 Go to previous messageGo to next message
Frank Naude
Messages: 4579
Registered: April 1998
Senior Member
You can make your log files much smaller, but 1 MB is a bit ridiculous. Two things to consider:

1. You will pay a performance penalty for switching log files too frequently; and

2. The minimum Log File Size for Oracle 10g is 4 MB (should preferably be > 10 MB).

Best regards.

Frank
Re: archive log file size [message #120757 is a reply to message #120718] Mon, 23 May 2005 09:57 Go to previous messageGo to next message
patrick
Messages: 83
Registered: December 2000
Member
frank i am willing to take the risk.

Can you tell me the steps to perform this task? I am using oracle 9.2. Size of logs would be 5 mb.

Patrick
Re: archive log file size [message #120759 is a reply to message #120757] Mon, 23 May 2005 10:02 Go to previous messageGo to next message
Frank Naude
Messages: 4579
Registered: April 1998
Senior Member
Hi,

You need to drop your current redo log groups and create new groups. See the chapter "Managing the Redo Log" in the "Oracle Database Administrator's Guide" for details and examples.

Best regards.

Frank
Re: archive log file size [message #120760 is a reply to message #120718] Mon, 23 May 2005 10:06 Go to previous messageGo to next message
patrick
Messages: 83
Registered: December 2000
Member
Ok thank you i'll look into that. If i have any questions i know where to find you. Smile

THANX
Re: archive log file size [message #120933 is a reply to message #120760] Tue, 24 May 2005 17:12 Go to previous messageGo to next message
DMcG
Messages: 51
Registered: May 2005
Location: Auckland, New Zealand
Member
The general rule of thumb for sizing of redo logs is to size them so that - on average - one gets filled up every 15 to 20 minutes.
You can check the frequency by setting the parameter LOG_CHECKPOINTS_TO_ALERT to True - This will record all checkpoints into the alert log. Checkpoints will occur every time a redo log is filled and the DB switches to the next one. As Frank says, 1Mb is pretty small for a redo log and you may well find that the excessive checkpointing that this causes affects the performance of your system quite badly.

The good thing is that you can fiddle with the redo logs while the system is live - as long as you're careful!

Dougie McGibbon
Re: archive log file size [message #120971 is a reply to message #120718] Wed, 25 May 2005 04:40 Go to previous message
patrick
Messages: 83
Registered: December 2000
Member
I have been real carefull with the changes and new redo log files are now 5 mb. This is perfect.

They are filling every 30 minutes and that is close enough.

Patrick

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