Oracle Metric redo log space requests

Oracle Consulting Tips by Burleson

The Oracle Documentation notes:

"The redo log space requests Oracle metric indicates the active log file is full and Oracle is waiting for disk space to be allocated for the redo log entries. Space is created by performing a log switch.

Small Log files in relation to the size of the SGA or the commit rate of the work load can cause problems. When the log switch occurs, Oracle must ensure that all committed dirty buffers are written to disk before switching to a new log file. If you have a large SGA full of dirty buffers and small redo log files, a log switch must wait for DBWR to write dirty buffers to disk before continuing.

Also examine the log file space and log file space switch wait events in V$SESSION_WAIT."

My notes on redo log space requests includes:

Oracle Redo Nowait Ratio

Oracle Remote Database alerts

Measure Oracle Redo Log Usage for SQL and DML

Oracle9i promises interesting enhancements

Oracle DBA Code Depot of Oracle SQL*Plus scripts

Code Depot: Automating Oracle Tuning

Oracle log buffer space

Oracle Database Trend Analysis Using STATSPACK

Oracle DBA Management Scripts Book & Code Depot

On Orafaq forums a user was having trouble with receiving too many, "redo log spacerequests in my prod db." The replier informed them that, "the ratio redo space request to redo entries if it is less than 1:5000 is considered good any thing bigger then have to increase log_buffers value.

This, and many other Oracle performance metrics are discussed in my book "Oracle Tuning" by Rampant TechPress. You can buy it directly from the publisher and save 30% at this link:

http://www.rampant-books.com/book_1002_oracle_tuning_definitive_reference_2nd_ed.htm

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