AIX

That's interesting, I suspect it means the AIX Diagnostic CD is supported:
AIX Diagnostics CD

That should give you boot media that will show and be able to test all the system hardware...

Agent.kgb: still "no Disks Detected" with RH LE 7.2

Going to the redpaper listed earlier - I saw also:

As the first thing that needs verification - are the disks visible to anything, or perhaps broken (so also using the diagnostics DVD is recommended).

If you can access the Web-based ASMI interface (either directly, or HMC as proxy) - also try a factory-reset of everything, and assuming physical access try installs without using the HMC.

At this point, a "simple" HW failure may be the cause, e.g., loose cable during transport.

Looks like VIO Server is off the table for now. As installed, your m/c doesn't support it. The next 3 items would be "True" if your m/c was ordered with Feature Code # EC22 & entitled to VIOS support.
AFAIK, the S812L comes in 3 orderable flavors:I dunno but I guess your machine was ordered with Feature code #EC16 - a basic machine...... leaving you with the bare metal options previously pointed out.

What to do now ? Some options I can think of:

From Diags screen, I only see the SAS RAID Adapter and Services Device. Do I suppose to see 2 SAS disks listed here. And Hit F7 to "commit" but it does not do anything :-(

+ sissas0 0 P1-C14-T1 PCIe3 x8 SAS RAID Internal Adapter 6Gb
+ ses0 P2-Y1 - SAS Enclosure Services Device
+ cd0 1 P2-D15 1 SATA DVD-RAM Drive

I will try to find other hard drive to replace it. But do I need to create RAID or it can bypass the RAID?

Thanks.

From the Diag utility, I'd expect to see devices behind your SAS RAID controller that look something like:RAID isn't needed. If RAID is not configured, they are just a bunch of disks (JBOD). Look for the RAID Array Manager in your Diag screens.... it will show you if any RAID configuration is present (provided the drives are readable)...... or not.

I find it odd that you would have 2 faulty drives right out of the box.... unless your e-bay supplier knowingly sold it that way. But what do I know ?

I assume you've re-seated the drives & even tried another disk slot ?

Diag -> Task Selection -> RAID Array Manager -> IBM SAS Disk Array Manager -> Create a SAS Disk Array -> sissas0 -> RAID 0 -> select a pdisk, if you see any, and make a hdisk from it. Then try to install RHEL again.