Good morning everybody,
a few weeks ago I ran into the problem of not having enough free space on my hard drive. The hard part is as following: "When I take the sum of all files present on my hard drive, it does not add up to the total amount of space used according to the system. Where has this space gone and how can I reclaim this?
When you save files on a computer system, it sits on what is known as a cluster.
Under Windows, each cluster has a certain fixed size depending on the size of the disk. The problem comes when you or any other program saves something to a cluster that doesn't fill that entire cluster.
So for example, your cluster size is 8 kilobytes. If you was to open Notepad, type one character and then save it on your hard drive, that 1 byte file would be saved to a cluster and therefore take up 8k of the hard drive. Nothing else can use that cluster until its empty, therefore 8,191 bytes have been wasted.
Across your hard drive as a whole, this sort of thing happens regularly where clusters aren't filled up. It's a necessary evil in order to be able to store data on hard drives. It's this behaviour (which is intended) that means you end up with two different figures for how much space is being used/available on the drive.
You can always convert the drive to NTFS to bring the cluster size down to 4 kilobytes, but it wouldn't regain you much in the way of space.