Size of data on disk looks wrong

  • Thread starter Thread starter Bob M
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Bob M

On my HP laptop, the "Properties" of the D: drive show 2.68GB used.
On a copy of everything on this drive, placed on a Desktop, the same data is
m731 MB. Both computers use Windows XP. The Laptop is Home Edition, while the
desktop is Media Center edition. Both use NTFS. "Hidden" and system files are
shown. Why such a large difference?
I read somewhere that the "Cluster size" of all NTFS drives is 4096 bytes, so
that would not explain the difference.
What am I missing?
 
On my HP laptop, the "Properties" of the D: drive show 2.68GB
used. On a copy of everything on this drive, placed on a Desktop,
the same data is m731 MB. Both computers use Windows XP. The
Laptop is Home Edition, while the desktop is Media Center edition.
Both use NTFS. "Hidden" and system files are shown. Why such a
large difference? I read somewhere that the "Cluster size" of all
NTFS drives is 4096 bytes, so that would not explain the
difference. What am I missing?
Click to expand...

Just as a guess, there's a system protected & hidden folder at the root
level named "System Volume Information" that contains the restore
points. That folder is typically inaccessible but can contain many
gigabytes of information as configured in:
Right-click "My Computer"->Properties->System Restore Tab.

HTH,
John
 
Just as a guess, there's a system protected & hidden folder at the root
level named "System Volume Information" that contains the restore
points. That folder is typically inaccessible but can contain many
gigabytes of information as configured in:
Right-click "My Computer"->Properties->System Restore Tab.

HTH,
John
Click to expand...

Thanks for replying. That could be a partial explanation of the difference,
but when I do as you suggest, it shows that it is set for a maximum file size
of 630MB. But even if I add that, it is still only about 1.6GB, not the 2.68GB
it is reporting.
When, in DOS, I go DIR /AHS /S /P It shows the SVI directory, but it has no
files and is zero size. There are many thumbs.db files shown, but they only
add up to 1.9MB.
I have the Tools, Folder Options,View setup to 1. Display contents of system
folders and 2. Show Hidden and System files. BUT: On the Home Edition Laptop,
I can't see the SVI listed, whereas on the Media..Desktop, the SVI does show.
Something very strange is lurking in there.
 
Might want to investigate/toggle the Registry key value for SuperHidden.
Key found at:
HKey_Current_User\Software\Microsoft\Windows\
CurrentVersion\Explorer\Advanced
 
Might want to investigate/toggle the Registry key value for SuperHidden.
Key found at:
HKey_Current_User\Software\Microsoft\Windows\
CurrentVersion\Explorer\Advanced
Click to expand...
Yes! That makes the System Volume Information folder visible.
That key was zero on the Laptop, and one on the desktop.
But: the size of SVI is still zero. And there are still 2.0 GB unaccounted
for.
 
You do understand that there are 2 distinct/different ways to show
usage 1.) Size 2.) Size on disk. The second takes into account what
is called "Slack Space". By default disk volumes use a 4-K Cluster
size. If you write a 1-Kbyte file into a cluster, the remaining space is
left unused or as Slack. So the file itself is 1-Kbyte but it consumes
a whole cluster so it's size on disk is = 4 Kbytes.
If your Right Click a primary folder ( Program Files, Windows..) and
take properties you'll see the following:

Size: 2.36 GB
Size on Disk: 2..87 GB

I missed your original post, so I don't quite follow how you determined
you've got missing disk space.
 
Bob M said:
Yes! That makes the System Volume Information folder visible.
That key was zero on the Laptop, and one on the desktop.
But: the size of SVI is still zero. And there are still 2.0 GB unaccounted
for.
Click to expand...

Have you taken into account your pagefile and hibernation file?

These are usually large. I'm don't think the pagefile would copy, but the
other might.
 
Have you taken into account your pagefile and hibernation file?

These are usually large. I'm don't think the pagefile would copy, but the
other might.
Click to expand...
Both of those files appear only on the C: drive. They do not show up on the D:
drive I am looking at.

I suspected fragmentation, but the software says the drive is not in need of
de-fragging. I may try it anyway.

FWIW, if I manually add up all the bytes of the top level directories it adds
up to approx 600 to 700meg, which is what my CD backup software agrees with.

Another possibly unrelated item: When I tried to make a copy of drive D: to
another empty drive, the software stopped with an error saying that The System
Volume Information directory was in use. It aborted, leaving only about 1/2
the data on the target drive. I did eventually get a good copy.

If all else fails, I will delete everything on the drive, and copy it back. I
am confident that the problem will be solved, but still, an unexplained 2GB is
disturbing.
 
If the data is backed up, then "Force" a Chkdsk D: /F on the drive.
It's possible the volume has space marked "Used" incorrectly. A
Fix pass with Chkdsk will force Windows to re-evaluate Free Space
on the volume and may fix the Bit Map data.
 
You do understand that there are 2 distinct/different ways to show
usage 1.) Size 2.) Size on disk. The second takes into account what
is called "Slack Space". By default disk volumes use a 4-K Cluster
size. If you write a 1-Kbyte file into a cluster, the remaining space is
left unused or as Slack. So the file itself is 1-Kbyte but it consumes
a whole cluster so it's size on disk is = 4 Kbytes.
If your Right Click a primary folder ( Program Files, Windows..) and
take properties you'll see the following:

Size: 2.36 GB
Size on Disk: 2..87 GB
Click to expand...
Yes, I am aware of the 4096 byte cluster size in NT. Older systems used a
cluster size which was different for each size of the drive.
I don't think the difference I am encountering could be due to the Slack
Space.
I missed your original post, so I don't quite follow how you determined
you've got missing disk space.
Click to expand...
The "Properties" for the D: drive says the used space is 2.68GB while a copy
of all the data to another computer is only 731Mb

When I look at the maximum size allowed for the system restore file, it says
it is set to about 600 to 700MB, but I don't see any file this size on the D:
drive. The System Volume Information Folder always reports xero size, so where
is the system restore file for D:?
 
Pro or Home ? - If Pro, add your Username to the ACL (Security )
(TAB) for System Volume Information and grant yourself Full Rights.
Once that is done you can navigate into SVI and see content. You
may have orphaned Restore Point Folders that need purging. If Home
you'll have to boot Safe Mode to make ACL changes.
 
If the data is backed up, then "Force" a Chkdsk D: /F on the drive.
It's possible the volume has space marked "Used" incorrectly. A
Fix pass with Chkdsk will force Windows to re-evaluate Free Space
on the volume and may fix the Bit Map data.
Click to expand...

CHKDSK? an old DOS program? Anyway, thanks to all who replied. That did fix
it. Now, the properties for D: say only 735MB is used. Much better!

What initially caught my attention was an Acronis True Image backup that
needed 2 DVDs to hold the data. I knew there wasn't that much on the drive.

CHKDSK said: "Deleting Orphan file record segment 2672"
"Chkdsk discovered free sapce marked as allocated in the Master File
Table (MFT) bitmap."
 
Bob M said:
Both of those files appear only on the C: drive. They do not show up on
the D:
drive I am looking at.

I suspected fragmentation, but the software says the drive is not in need
of
de-fragging. I may try it anyway.
Click to expand...

De-frag has nothing to do with file size,
FWIW, if I manually add up all the bytes of the top level directories it
adds
up to approx 600 to 700meg, which is what my CD backup software agrees
with.

Another possibly unrelated item: When I tried to make a copy of drive D:
to
another empty drive, the software stopped with an error saying that The
System
Volume Information directory was in use. It aborted, leaving only about
1/2
the data on the target drive. I did eventually get a good copy.
Click to expand...

Generally; files in use, some system files, or directories you don't have
permissions for won't be copied.

It's a failing of Windows that when such a message appears there is no
button "skip" or "ignore file" so you can at least copy the rest of the
files you selected initially.
If all else fails, I will delete everything on the drive, and copy it
back. I
am confident that the problem will be solved, but still, an unexplained
2GB is
disturbing.
Click to expand...

I read the post about chkdsk fixing your problem. You must not run it very
often or have some other problems to have such a large amount of unused
space reported as in use.

The error checking tool under the drive properties is just a GUI for chkdsk,
and even though it shares the same name as an old DOS program, these things
do "evolve".

Glad to see your problem solved.
 
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