MattiP,   I would start with powering down the server, remove the power cables, hold the power button for 20 seconds  (drains flea power). After that then reseat the raid chain, basically the raid controller, the backplane cables, the backplane, and the drives. I would also highly recommend that you update the server on BIOS, iDrac, H730P, and the drives (if available).   Let me know what you see.    
Hello, I have a Dell T630 which HDDs keeps going off, bays for those HDDs are missing too, not showing in BIOS settings under PERC. Controller type is PERC H730P 12Gb PCIe 3.0 x8 2x SFF-8643 Raid Controller 2GB Cache. There is one virtual disk RAID 5 with 8x2,5" 1,8 TB 10k SAS 12G Raid Enterprise Storage 24/7 HDD. Two "rows" of 8 similar disks per row and the upper 8 is in use, and the lower 8 disks just waiting for configuration. But. 0) Initially server was ok with HDDs. 1) HDD on bay 0:0:7 broke first on the very first day of production use, was replaced succesfully and then this HDD broke again in 2 months. Had to do "foreign" configuration reset fist for the replacement HDD, but after that worked. 2) New replaced disk broke in ~1 month, in the slot 0:0:7. All leds were off in this particular disk. 3) Now a HDD in 0:1:15 had died, leds off. Put a new quarantee replacement HDD (brand new) in 0:0:7, it was dead on arrival. All leds off in these two disks. 4) Swap a working HDD from 0:1:14 --> 0:0:7 and worked fine in here. And vice versa, now 0:1:14 bay with dead disk is dead, all leds off in this disk. 5) Also tried to swap 0:1:14 <-> 0:1:15 but no difference. Leds are off in these bays, where dead HDDs are in. They (bays or disks) don't show up in BIOS, under PERC H730 config. Every time I have switched off the server before operations, grounding myself, so no mistreatment of HDDs or server. It is hard to believe that this server eats HDDs every 2 months. Any ideas? Thank you in advance. iDRAC is version 8. Br Matti
Dell T630 Dell PERC H730P and missing disks