RE: Recommended number of redo log switches per hour

Jeremiah,

You are in a bit of an unusual situation, most databases are not producing 5 to 10 Gb every 20 minutes. I grant the facts regarding instance recovery time and standby's. These should certainly be taken into consideration. However, it does seem frequent checkpoints are going to add overhead and that reducing the number of checkpoints which occur during periods of high activity would be beneficial. I usually go with large redo logs (as large as possible) and control me checkpointing with parameters if I have an SLA to meet. So I don't think clock time is completely out of the question.

• Ethan

-----Original Message-----
Sent: Thursday, March 14, 2002 10:19 AM
To: Multiple recipients of list ORACLE-L

On Thu, 14 Mar 2002, Khedr, Waleed wrote:

> In my opinion not less than 5-10 minutes in very busy times.

The three log switches per hour reccomendation from Oracle support is delusional. I would need 5 to 10 Gb logfiles to accomodate that reccomendation. And any standby would be miserably behind at all times. And recovery time (assuming log switch checkpoints) on instance failure would be unacceptable.

Wall clock time is a bad metric for this question, and support should not have told Patrice this.

If checkpoints are usually able to finish before the next log switch, then the logfile sizes are fine.

Robert F., Here's one for ya.

--
Jeremiah Wilton
http://www.speakeasy.net/~jwilton

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