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Relink Oracle after OS upgrade [message #679771] Wed, 25 March 2020 08:30 Go to next message
John Watson
Messages: 8348
Registered: January 2010
Location: Global Village
Senior Member
I am having to upgrade a Linux kernel from 3.10.0 to 4.14.35 and I have to make the downtime as short as possible.
The machine has all the Oracle Homes and databases on one file system. The technique I am looking at is to prepare a new machine, unmount the file system from the old machine, and mount it on the new machine. It all seems to work.
The question I have is whether I need to relink the Oracle Homes. The definitive guide should be MOS,

Relinking Oracle Home FAQ ( Frequently Asked Questions) (Doc ID 1467060.1)

The relevant section is:Quote:
4) When Manual relinking is required?
Manual relinking is required in below situations.

A) After OS upgrade, Generally OS 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.

"However Oracle recommends performing manual relinking of Oracle Home binaries after OS upgrade". Hardware changes does not require relinking.

B) After Operating system has been patched.( Recommended ).
There is also this:Quote:
5) Is relinking required after an OS upgrade , Downgrade , Patching or removal of the patch ?
Yes, Oracle recommends to perform manual relinking of Oracle Home Binaries after OS Upgrade , Patching , Downgrade or removal of the Patch or any change which impact OS library behavior . Successful relinking shows Oracle Executable are properly linked with OS binaries.
And the "Administrator's Reference for Linux and UNIX System-Based Operating Systems" says:Quote:
3.2 Relinking Executables
You can relink the product executables manually by using the relink shell script located in the $ORACLE_HOME/bin directory. You must relink the product executables every time you apply an operating system patch or after an operating system upgrade.
All this seems to be saying that I don't need to relink, but I can if I happen to feel like it. On this machine (it is an AWS EC2 with only 2 vCPUs) the relink takes nearly 5 minutes per home and there are several homes. Without the relink, it all seems to work.

And there are articles such as this
https://serverfault.com/questions/37557/when-to-relink-oracle
that saysQuote:
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.
but I cannot find the doc he is talking about.

So my question is, does anyone have an opinion on this? Do you relink after (for example) a yum update or don't you bother? Also, are there any sort of tests I could do to check if the relink really is necessary?

Thank you for any insight.
Re: Relink Oracle after OS upgrade [message #679772 is a reply to message #679771] Wed, 25 March 2020 09:20 Go to previous messageGo to next message
John Watson
Messages: 8348
Registered: January 2010
Location: Global Village
Senior Member
I've just had one suggestion - to do it with Data Guard switchover. Perfect! Except that these are SE licences Sad
Re: Relink Oracle after OS upgrade [message #679773 is a reply to message #679772] Wed, 25 March 2020 09:33 Go to previous messageGo to next message
BlackSwan
Messages: 26733
Registered: January 2009
Location: SoCal
Senior Member
In theory, there is nothing stopping you from reinventing the wheel & implementing Roll Your Own Data Guard solution.
I did it more than a decade ago on SE to avoid EE licensing fees.
Re: Relink Oracle after OS upgrade [message #679774 is a reply to message #679773] Wed, 25 March 2020 10:03 Go to previous message
John Watson
Messages: 8348
Registered: January 2010
Location: Global Village
Senior Member
One of the databases on that machine already has a manual standby (log switches every 10 mins, an NFS export to make the archives visible to the remote machine, a cron job to apply them) so perhaps I could add standbys for the others. I'll look into this. Thank you.
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