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Old October 20th 13, 05:33 AM posted to microsoft.public.windowsxp.hardware
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Default Disk Uses More Space Than Size of Files

W wrote:

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?

Did you include hidden-marked files? Did you configure Windows Explorer
to show hidden-marked files?

Did you include special and OS files not shown by Windows Explorer? Did
you include the pagefile and hibernate files? You didn't explicitly
state this was a non-OS partition. Even if it is not an OS partition,
but if the partition is on a different hard disk, often users will
spread the pagefile across multiple hard disks so reads can be queued at
the same time to the pagefile along with those to the OS partition.
Maybe the pagefile portion in the problematic partition, if enabled, is
set way too huge.

Is that partition only for use by your backup program? And that backup
is which one? Some backup programs provide for snapshots. They
deliberately hide those snapshots from the file system, so what you see
in Windows Explorer won't reflect the space consumed by the snapshots.
Then there are other "restore" utilities, like Comodo's Time Machine
(don't ever try using this betaware) or DeepFreeze, that take snaphots
of the file system and hide them from the OS. If you are using
virtualized disk I/O utilities to provide a safe environment for testing
unknown or untrusted software (just the disk is virtualized and all
other hardware is real) instead of an always slower virtual machine,
like Returnil, they hide their disk space used by their replacement file
I/O handler to virtualize disk I/O. Some folks have this setup to use
half of the available free space. It isn't in use when you are not in
"safe mode" (when virtualized disk is active) so that space is
available; however, once you go into safe (virtualized disk) mode then
that space gets used. While virtualize disk I/O is active, that space
can get consumed. When you reboot, all changes to the virtual disk are
discarded and you're back to using the real disk I/O. The paid version
lets you incorporate all changes to the virtual disk onto the real disk.
Are you using any kind of this software that might be reserving disk
space while it is active? Returnil, for example, can be set to always
boot into safe mode so the only way out is to have admin rights to
change its config to not boot into safe mode and to be back to real disk
mode. SteadyState and other products do similar disk virtualizing so
all changes can be discarded but you have direct access to all other
hardware so, for example, your video game runs at full speed using the
real video card instead of an emulated one used inside virtual machines.

If you are doing regular/daily backups then you really don't need System
Restore. Disable System Restore (at least on that partition) which will
delete all restore points for that partition. Restore points won't
include you backup files, anyway, so there's no point in enabling System
Restore on that partition.