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Donald K. Burleson
Oracle Tips |
Oracle Archives – archived
redo logs
If you alter the setting of the
COMPATIBLE initialization parameter, it will most likely render all
previously generated archive logs as unusable for recovery. Always
perform a complete backup after changing the value of the COMPATIBLE
parameter. Anytime a startup is performed using the RESETLOGS
parameter, all previous archive logs become invalid and may not be
used to recover the instance after the startup.
If you are using Oracle parallel server (now called RAC), all
archive logs generated from all redo threads must be available to
all instances. Usually this is accomplished by using a cron script
to copy the archive logs to multiple locations. Another possible
solution is to copy the archive logs to a central NFS (Network File
System) mounted disk farm; however, if the NFS mount point is lost,
you won’t be able to recover, so be sure the NFS mount is on a
high-reliability server. Never set LOG_ARCHIVE_DEST for archive logs
to raw devices; remember that only one file is allowed per RAW area,
so each new archive log would overwrite the previous in a raw
destination.
In Oracle8i and Oracle, multiple archive log locations are
allowed, even on other platforms reachable through the network. This
makes administrating standby databases much easier to automate.
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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