If you create new partitions with fdisk you would need to restart the system since a funny message warning you about that, to re-read the new partition table, you need to reboot.
But with a parted (another like-fdisk partition tool) included command called partprobe, it will re-read the new partitioning and send the changes to the kernel requesting a new re-read without reboot.
After fdisk partitioning, type the command:
# partprobe
Again, in order to use partprobe command you need to install parted
Note*: Update from RedHat, they have said that on new RedHat OS release versions this partprobe behaviour will be removed, as they consider this usefull way to save a reboot in a production machine as a bug!!!…