What's up with my 8th drive on my crossflashed PERC card?

Hey guys, I’m pretty new to TrueNAS and servers in general, so I’ll try to explain what’s going on here as best I can.

I’ll start with some information on my server. It’s a PowerEdge R520 with 2 e5 2470 v2 CPUs, 192 GB of DDR3 ECC, a crossflashed PERC H710 mini raid card, 8x 1TB seagate barracude HDDs, and running TrueNAS Scale 24.10.0 Electric Eel.

For some context on the problem, I heard it was a pretty good idea to crossflash PERC cards to standard LSI firmware/IT mode as hardware raid is pretty much dead. I followed the Fohdeesha docs H710 D1 guide on crossflashing.

Now, before this I had set up each drive in its own raid 0 so truenas could handle them, as the perc firmware is trash and doesn’t have an option to act as a normal HBA.

Here’s where the problem comes in. After crossflashing the card to IT mode, only 7 of my drives show up in truenas. More specifically, one of my bays isn’t recognized in truenas, as I swapped the drive out for another, and it still doesn’t show up. I reseated the perc card, cables on both ends, the drives, pulled power and rebooted about a thousand times. And alas, only 7 drives show up.

I know for a fact it isn’t a connection problem, since everything works just fine on the stock perc firmware. I could only find one other post about this issue, but I can’t link it unfortunately.

I tried what they suggested at the end of that post I saw, moving one of the backplane cables to the onboard sata controller, and that seems to get all the drives to show up, but idrac seems pretty pissed that the cables aren’t running where they should. Also in that post they mentioned all drives showing up in another OS, it’s just truenas specifically that doesn’t recognize everything. I haven’t tried another OS yet, but I have the feeling it would work.

So at the moment it looks like a truenas issue, but I have no idea how to go about solving it, if there even is a solution. Hopefully someone here can help out with this, and thanks for reading.

Did you by any chance try a different OS such as a regular Linux variant on the system with the card flashed into IT mode? You mention it looks like a TrueNAS issue but to confirm this I’d suggest trying a regular Debian install and see if it can see all 8 of the drives. If it can I’d agree something is not quite right but if it can’t it still sounds like a hardware issue.