This white paper explains why Oracle Database runs best on Oracle Linux: https://www.oracle.com/a/ocom/docs/linux-for-oracle-database-wp-2068570.pdf (last updated in May 2020).
Also, you do not need to relink after updating with Ksplice, even if you patch your glibc using Ksplice for user space.
That is music to my ears!
Note that the same is true for Oracle Database on Oracle Linux 7: you don't need to relink after updating via Ksplice.
You cannot compare OL and AIX unless you want to compare apples and oranges. There are too many differences in system administration and design philosophy. Every modern operating system worth mentioning maintains full user space compatibility when applying patches.
The Linux kernel is backwards compatible and hence programs are backwards compatible too. Libraries like kernel-headers and glibc are not forward compatible. Kernel-headers comes into play when you compile kernel drivers. The glibc library defines user space compatibility.
The following seems interesting:
If you check the available Linux patches for the previous OS releases like OL 6 and 7, which you can do browsing the software repository, such as here for example, you will see that there are no glibc patches.
Linux system calls are extremely stable. New kernel versions do not introduce new system calls unless required to take advantage of new CPU features or required by CPU architecture. Such modifications require a complete re-installation of the operating system.
You need to pay attention to Linux kernel version changes if you have installed kernel drivers that are installed by the Oracle database installation. There are a few kernel drivers that are not open-source and hence Oracle cannot include them in the Linux kernel or OS distribution. For example, ASM/ACFS kernel driver. Simply relinking the Database, however, won't address the issue.
I would not have any sleepless nights over not relinking Oracle database binaries after installing Linux OS patches. The recommendation or requirement to relink Oracle database binaries according to the documentation isn't OS specific. As far as I'm aware it is simply another safeguard that stems from the fact that the Oracle database installation isn't maintained or known by OS software installation management.
Is there a reference note regarding not needing to relink? Also, if we don't use ksplice would we need to relink?
Also can we use NUMA and VMWare together? What happens to assigned resources that are not being used? Can they be used by other vms? I would like to have guaranteed resources, but I don't want to "un-consolidate" or database environments if we don't need to.
You'd have to ask the Database folks about any reference notes.
Also, I'm not sure about vNUMA and VMware. I know we support it on Oracle Linux KVM (and newer releases of Oracle VM) but I'm not sure what happens on VMware, to be honest.