THE PROBLEM
We've all been there. The server is toast. It's not booting and something seems really odd.
Sure, there are recovery boot options with most operating systems and a collection of helpful ISOs out there to assist. Good examples might be the System Rescue CD, a Knoppix liveCD, or even the built-in rescue boot of CentOS / Red Hat Enterprise Linux. But what if the problem seems to be within the hardware or related to it?
There are vendor tool DVDs available, such as HP/HPE's ServicePack for Proliant (SPP) or Dell's System Update. These contain useful hardware diagnostics and tools that would be perfect for a recovery environment. Except, they're not available in any recovery environment.
I suspect that actually distributing a recovery disk with 3rd party closed-source tools on would run into some copyright issues. However, presuming we can get hold of the tools/drivers needed it seems like a useful thing to build ourselves and keep around.
THE REAL QUESTION
Has anyone ever built something like this? How did you do it? What issues did you run into?
If you're referring to modern HPE ProLiant hardware, there's really no need for an external recovery disk/utility.
HPE servers since the Generation 8 series (2012) have the Intelligent Provisioning feature built in. It provides and preinstallation, configuration, firmware management and diagnostics environment integral to the hardware. But even this is rarely needed...
If there's a hardware problem on an HP server, the ILO has the Integrated Management Log and ILO Event Log available.
In addition, the Systems Insight Display gives you a visual status of the hardware components.
What type of issue are you envisioning that isn't covered by the above diagnostic approaches?
Edit:
The Linux firmware update for your disks is located here. It is version HPG3. This disk, MM1000EBKAF, has not been included in HP SPP distributions, so you will have to update them manually.
You can wget the .scexe file to a running Linux OS or Live CD and run the firmware update that way.