Unconfigured means its in offline state and the disk can be replaced:
~# megacli -PDList -aAll | egrep "Enclosure Device ID:|Slot Number:|Inquiry Data:|Error Count:|state" Enclosure Device ID: 252 Slot Number: 0 Media Error Count: 0 Other Error Count: 0 Firmware state: Online, Spun Up Inquiry Data: HITACHI HUC109090CSS600 A5B0KPV3WH0F Enclosure Device ID: 252 Slot Number: 1 Media Error Count: 0 Other Error Count: 32 Firmware state: Unconfigured(good), Spun down Inquiry Data: HITACHI HUC109090CSS601 MS06KPVJ9UYF Enclosure Device ID: 252 Slot Number: 2 Media Error Count: 0 Other Error Count: 0 Firmware state: Online, Spun Up Inquiry Data: HITACHI HUC109090CSS600 A5B0KPWHM73L Enclosure Device ID: 252 Slot Number: 3 Media Error Count: 0 Other Error Count: 0 Firmware state: Online, Spun Up Inquiry Data: HITACHI HUC109090CSS600 MS06KXHE2JAR