When to relink Oracle?

I have rarely needed to relink Oracle database, maybe only after major O/S upgrade or going from 32-bit to 64-bit. However, if you have doubts, just run it. It takes a minute. Another source to consult with is metalink note 131321.1... the gist is:

" Relinking occurs automatically under these circumstances:

• An Oracle product has been installed with an Oracle provided installer.
• An Oracle patch set has been applied via an Oracle provided installer.

The following information has been added to the 'Certify' section of Metalink:

General Notes For Oracle Database - Enterprise Edition:

O/S Information: The vendors guarantee operating system binary compatibility; therefore, no reinstall or relink of the Oracle software is required when upgrading these operating systems unless specifically stated otherwise.

Relinking Oracle manually is suggested under the following circumstances (even though the OS vendor may not require it):

• An OS upgrade has occurred.
• A change has been made to the OS system libraries. This can occur during the application of an OS patch.
• A new install failed during the relinking phase.
• Individual Oracle executables core dump during initial startup.
• An individual Oracle patch has been applied (however, explicit relink instructions are usually either included in the README or integrated into the patch install script)

"

For a complete picture, in additionan to what was said above, Oracle Clusterware may also need relink if you're changing Linux kernel. For example if you use ACFS filesystem, Oracle has ACFS kernel drivers for a specific Linux kernel version. Not sure if minor kernel upgrades qualify for this though.

It's not actually a relink itself that fixes acfs Clusterware drivers, but crs/install/rootcrs.pl -lock (or roothas.pl -lock for a single-node clusterware) script that installs new ACFS drivers. You'll have to call rootcrs.pl -unlock before relinking clusterware binaries, and once relinking is done - then rootcrs.pl -lock .