Can't partition Harddisk using GParted Partition Editor on ubuntu 12.04

[vtnt]

Hi,

When trying to use GParted Partition Editor I can see my wholde harddisk /dev/sda1

The row is like
Partition: /dev/sda1
File System:ext4
Mount Point: /
Size: 456GB
used: 16GB
Flags: Boot

When I try to create partition Table I get following message

2 partitions are currently active on device /dev/sda.
A new partition table cannot be created when there are active partitions. Active partitions are those that are in use, such as a mounted file system, or enabled swap space.
Use Partition menu options, such as unmount or swapoff, to deactivate all partitions on this device before creating a new partition table.

So I try to unmount using Gparted I get following message

Could not unmount /dev/sda1
The partition could not be unmounted from the following mount points:
/
Most likely other partitions are also mounted on these mount points. You are advised to unmount them manually.

please help.

Thanks,
vtnt.

[ahallubuntu]

~

[Mark Phelps]

As a note ... "sda1" is NOT your whole "hard disk"; instead, it is the first (and possibly, only) partition on your hard disk.

The disk itself is referred to as "sda".

The partitions are referred to as "sda1", "sda2", etc.