You added a LSI 12Gb SAS card in your server (Dell R20, R630, R730 or others) and the card is unknown by the server? Here there is the solution, you can just follow the post step by step. 😉
The problem come from VMware. Basically, upgrading VMware ESXi firmwares (in 5.1 or 5.5) drops the driver of this card: LSI 12Gb SAS 9300-8e HBA (OEM). I think other LSI cards should be concerned. Your card is not listed in the bios, you can checking the material inventory in iDRAC interface. So, the goal will to add the .VIB package of this card in ESXi system.