I wanted to put together a guide for new owners of 12th Generation Dell servers. Over the course of owning few 12th Generation Dell Servers (Rx20), I have come across few common issues encountered during firmware upgrades and I wanted to share my advice on overcoming them.
It's very important to observe caution while upgrading iDRAC Firmwares to prevent issues like this, this, this and this. When these 12th Generation servers were shipped, the iDRAC and LifeCycle controller had different firmware. In Late 2014, Dell has decided to integrate the iDRAC and LifeCycle Controller firmwares into a single package called "Dell iDRAC with LifeCycle Controller" and the firmware is now common across iDRAC 7 and iDRAC8. The partition layout for the iDRAC eMMC was changed, due to which upgrades across legacy firmwares and the latest firmwares were failing, which was causing iDRAC to be permanently bricked with no resolution except for a motherboard replacement as of now. 18.104.22.168,A00 was the first firmware release for Dell iDRAC with LifeCycle Controller.
If your iDRAC version is higher than 22.214.171.124, then you could directly upgrade to the latest version of the iDRAC firmware without running into any issues. As of writing, 126.96.36.199 is the latest iDRAC firmware.
If your iDRAC version is lower then 188.8.131.52, DON'T UPGRADE TO THE LATEST VERSION OF THE iDRAC. UPGRADE YOUR FIRMWARE TO 1.66.65,A00 (LAST STANDALONE FIRMWARE) AND THEN UPGRADE TO 184.108.40.206,A00 (FIRST RELEASE OF COMMON FIRMWARE) AFTER WHICH YOU COULD DIRECTLY UPGRADE TO THE LATEST FIRMWARE AVAILABLE.
Power Supply Firmware
If you google for "dell psu bricked", you will come across many posts about people bricking their Dell server Power supplies during firmware upgrades. 12th Generation servers included firmwares for power supplies which can be upgraded just like any other components. However, the upgrade process was flawed and this resulted in several power supply bricks. More info here.
Dell no longer provides PSU firmware upgrades in Dell SUU ISO files and you will have to upgrade the firmware manually. I would personally recommend upgrading the firmware only if you are facing any issues with the PSU.
Never run the power supply upgrade if you have 2 power supplies installed in the server which belong to the same manufacturer. Always remove one power supply and upgrade it one at a time. Although Dell doesn't explicitly state this as required, it's better to upgrade one at a time to prevent both PSUs getting bricked due to a faulty firmware.
The server would power off for a period of upto 15 minutes for the power supply firmware upgrade to complete. Don't unplug the power supply or switch on the server.
Once the firmware upgrade for the power supply completes, the server will automatically boot.
Avoid using iDRAC Virtual console for mounting SUU ISO
If you remotely mount a SUU ISO containing the firmware upgrades and boot it using iDRAC Virtual media, bear in mind that any updates to the iDRAC itself will kill the virtual media connection thereby possibly causing damage. A NIC update would also kill the connection if you decide to use the network LOM port for iDRAC instead of the dedicated port. Always create a bootable CD/USB drive and boot off it to upgrade your firmware.