To check hardisk information such as model and serial number, there are a few useful commands like hdparm, sdparm and fdisk.
To check the information about first hardisk for PATA and SATA hardisk:
# hdparm -i /dev/sda
For SCSI disk, a different command is to be used:
# sdparm /dev/sda
To check the hardisk capacity and partitions contained in the hardisk, fdisk can be used:
# fdisk -lu /dev/sda
If your hardisk is smart compatible, you can refer here on how to install and use smart to find information and monitor the health of your hardisk.