PERC S300 Dell 3Gb/s SAS/SATA Internal Software RAID Adapter 4x3.5" Chassis for T110 - 342-3349
Finally got it working! Now the real fun begins 🤩😃 (Turns out the PERC S300 doesn't like anything but Windows, so had to fix that with a H700 off of ebay) :
Solved: Degraded disk Dell Perc S300 | Experts Exchange
Perc S100/S110/S300:ソフトウェアRAIDで障害が発生したハード ドライブを交換する方法 | Dell 日本
SOLVED] RAID 1 rebuild on PowerEdge T410 with PERC S100 - Dell Hardware
DELL PERC S300 3GB SAS RAID CONTROLLER 0 /1 /5 U558P - cmicomputer.com
Solved: Perc s300 not detecting drives - Dell Community