HP ProLiant ML350 Generation 4p User Manual page 21

SATA models of the HP ProLiant ML350 Generation 4p server support up to six
hard drives. The embedded SATA controller supports drives in bays 1 and 2
(SATA IDs 1 and 2). An optional controller is required to support drives in bays
3 through 6 (SATA IDs 3 through 6). The hot-plug SATA drive cage also
supports 8.89-cm (3.5-in) SAS hot-plug hard drives. An optional SAS controller
is required to support SAS drives.
Item Description
1 Hot-plug SCSI hard drive cage
2 Hot-plug SATA hard drive cage (SAS-enabled)
Server Component Identification 21