I ran into a strange problem yesterday, where a Linux system was able to boot from its SATA drive, and everything seemed fully functional. However, there was no entry for /dev/sda (the usual entry for the first SATA drive). Thus, I could not use fdisk to create a new partition. It turns out there is a script called MAKEDEV which solved this problem for me. I simply ran `cd /dev; MAKEDEV sda` and the entry was created. fdisk worked just fine.