Today Hans Reiser was found guilty of first degree murder in Oakland, California – In a murder case with no body, no crime scene, no reliable eyewitness and virtually no physical evidence, the prosecution began the trial last last November.
If you are using hot swappable hard disk and created new partition using fdisk then you need to reboot Linux based system to get partition recognized. Without reboot you will NOT able to create filesystem on your newly created or modified partitions with the mke2fs command.
However with partprobe command you should able to create a new file system without rebooting the box. It is a program that informs the operating system kernel of partition table changes, by requesting that the operating system re-read the partition table.