Disk Uses More Space Than Size of Files
I have a 1 TB NTFS partition on Windows XP that reports through Explorer
Properties dialog as having 70GB available. When I add up the size of all
of the files on disk, there should be 350GB available.
I am very aware of cluster sizes and how many small files would take up the
minimum cluster size, usually 4096 bytes per file. The problem is the
partition in question only holds huge backup files, minimum 1 GB in size.
So there are no small files on the partition that would waste empty sections
of each cluster.
I emptied the Recycle Bin, so deleted files are not accounting for this
What would account for the waste of space being reported by the OS? What
tools might help me to explore this further?
The mystery area is probably System Volume Information.
Make sure System Restore is not "tracking" your backup drive.
WinXP tends to turn that on by default, each time a new drive
is connected. I have System Restore turned off on WinXP now.
So that's no longer an issue. Turning off System Restore,
does not remove SVI folder, neither does it disable
VSS service (which is used when backing up a partition
with a modern backup tool).
I wish there was an easy way to visualize what's in there,
so I could do more testing on this.
You could try ShadowExplorer, which is supposed to make
visible things that are being shadowed (and hidden) inside
SVI. But ShadowExplorer doesn't show you everything
stored in SVI. In WinXP, you see lots of RPxx folders
for restore points, as a major contributor to bloat.
Turning off System Restore, should make those go away
(on all your partitions, not just the one you're concerned
about right now). It really depends on whether you consider
System Restore to be worthwhile, as to whether it should
stay turned on. When you do Windows Update, that is one time
it's nice to have it turned on, just in case.
I boot a Linux LiveCD for a look inside System Volume Information.
On Vista/Win7/Win8, it's possible to trash the OS by screwing
around in that folder. So take precautions before becoming
too adventurous. I had to restore my laptop from a backup,
after one of my little experiments ran amok. And using the
Linux LiveCD was all part of that (causing the problem) :-)
One of my Linux LiveCD collection, the Knoppix 5.3.1 DVD,
mounts all partitions read-only. And while I don't use
that disc regularly any more, that's the only one I trust
not to trash stuff. It's like a gun with a safety -
you can still turn off the safety on that LiveCD environment,
and trash stuff. But it stops you, if you're a noob at it.
To go read/write, takes an extra step.