Donald K. Burleson
Oracle Number and
Placement of Redo Logs?
You have to balance
the needs for restoration and minimal data loss against time to
recover data. Obviously, if you have archiving happening every
minute and your normal workday is eight hours, you will have 480
logs written to disk daily. Over a five-day workweek, this turns
into 2,400 files. If you have to restore from a crash or other
disaster, you may have to apply all of these to your last backup to
bring the database current to the time of the crash. In one case, a
DBA had to apply 9,000-plus files to recover his system because he
hadn’t looked at how often his redo logs were archiving. Needless to
say, he pays more attention now. The minimum size for redo log
groups is 50 KB. By default the Oracle DBCA creates 100 megabyte
In Chapter 12 on database tuning, we will discuss how to determine
if you have a sufficient number of redo log groups and how to
optimize your archive process.
This is an
excerpt by Mike Ault’s book “Oracle
Administration & Management”. If you want more current Oracle tips
by Mike Ault, check out his new book “Mike
Ault’s Oracle Internals Monitoring & Tuning Scripts” or
Ault’s Oracle Scripts Download.
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