Re-Mount /etc/fstab without Restarting

You have added new entry in your /etc/fstab file to mount a drive or partition. To mount those new partitions you would normally reboot your PC. There is a simple way which will Re-Mount the drives in your /etc/fstab file. Run as root.
mount -a

The above method remounts

The above method remounts all filesystems described in /etc/fstab.

Alternatively to remount only one, you could use

mount -o remount /

OR

mount -o remount /dev/sda1

The first one is preferred as you need not know the device name and number for the / partition.