File size different on disk and copied file Why?

[Spikey]

Can someone explain why file properties say eg. 20mb 2 folders 7 files but
size on disk will be slightly larger at 20.02 mb 2 folders 7 files? I'm used
to seeing this difference but unsure why it does it.

Also if you took an exact copy (with hidden files viewable) of the original
20mb 2 folders 7files on to another drive why would it state the files on
disk as lower than the original eg size on disk 20.1.

I've just copied hubbies my docs to his D drive, and then I'm backing the
original my docs to disk before deleting. Hes been cramming everthing on C
and was oblivious to the big empty unused expanse of D where they probably
should have been in the first place!!!!

I've compared the 2 copies 1 still on C and everything has copied, nothing
missing. But I have this nagging doubt as the file on disk size is reporting
magianlly less.

Finally there were a couple of small game saves (we think) on D. Given that
hes always saved to his docs which were targeted to C docs and setting etc,
how did they get there (excluding user error)? Would an Acer (XP home)
laptop be capable of automatically start saving to D if C was overflowing? I
realise its all the same drive but my understanding was that once
partitioned they are regarded as 2 separate drives.

Thank in advance.

)

 

[paulmd]

Can someone explain why file properties say eg. 20mb 2 folders 7 files but
size on disk will be slightly larger at 20.02 mb 2 folders 7 files? I'm used
to seeing this difference but unsure why it does it.

Also if you took an exact copy (with hidden files viewable) of the original
20mb 2 folders 7files on to another drive why would it state the files on
disk as lower than the original eg size on disk 20.1.

I've just copied hubbies my docs to his D drive, and then I'm backing the
original my docs to disk before deleting. Hes been cramming everthing on C
and was oblivious to the big empty unused expanse of D where they probably
should have been in the first place!!!!

I've compared the 2 copies 1 still on C and everything has copied, nothing
missing. But I have this nagging doubt as the file on disk size is reporting
magianlly less.

Finally there were a couple of small game saves (we think) on D. Given that
hes always saved to his docs which were targeted to C docs and setting etc,
how did they get there (excluding user error)? Would an Acer (XP home)
laptop be capable of automatically start saving to D if C was overflowing? I
realise its all the same drive but my understanding was that once
partitioned they are regarded as 2 separate drives.

Thank in advance.

)

http://en.wikipedia.org/wiki/Cluster_(file_system)

 

[Spikey]

http://en.wikipedia.org/wiki/Cluster_(file_system)

I had looked there but hadnt found exactly what I wanted. Which sub heading
are you looking to at?

Any idea on the other questions?

 

[Wesley Vogel]

File Slack.

In data storage, the smallest amount of disk space that can be allocated to
hold a file is called a cluster. Most files are not the same size as the
cluster size on a hard disk. The difference between the actual file size
and the cluster size is called file slack. File slack is wasted space.
There will always be wasted space no matter what size the clusters are.
File size plus file slack equals Size on disk.

If your hard drive has 4KB cluster size and you have a file that is 1KB,
File Properties will show:

Size: 1.00KB (1,024 bytes)
Size on Disk: 4.00KB (4,096 bytes)

Size is the actual size of file's (or folder's) data.

Size on disk is the actual space that the file (or folder) takes up on the
hard drive.

What File Properties does not show is the file slack. From the example
above, the file slack would be 3KB (2,048 bytes) of wasted space.

KB (kilobyte) is a binary number, 2 to the tenth power, 2^10
or 1,024 bytes. So 1KB is 1,024 bytes, not 1000 bytes like we would
normally think of using decimal numbers

For best overall file system performance, a 4KB cluster size is best.

If the cluster size is too large, there is more file slack.

If the cluster size is too small, there will be more fragmentation.

The smaller the cluster size, the more efficiently a disk stores information
because unused space within a cluster cannot be used by other files.

You can find the cluster size, also called allocation unit, by looking at
the chkdsk log in the Event Viewer.

Open the Event Viewer...
Start | Run | Type: eventvwr | Click OK |
Look in Application | Listed as Information |
Event ID: 1001
Source: Winlogon

Similar to this:
4096 bytes in each allocation unit.

How to locate and correct disk space problems on NTFS volumes in Windows XP
http://support.microsoft.com/kb/315688

Disk Quota Charges Increase If You Turn On the NTFS Compression
Functionality
http://support.microsoft.com/kb/320686

Binary vs. Decimal Measurements
http://www.pcguide.com/intro/fun/bindec.htm

--
Hope this helps. Let us know.

Wes
MS-MVP Windows Shell/User

In

 

[Spikey]

Would an Acer
Thanks Wesley, I've got a much better understanding of it now.
Its reporting 4 KB clusters. I assume thats a default setting when you use
NTFS instead of fat32/16?

Any idea on the "overflow" query? He's using the laptop on the original
settings it came with. But I assumed it was standard notebook set up to
target "My Documents" to D:\ when the drive is partitioned. I suppose on
first use he may have been given a choice of saving to C:\ or D:\ ?

)

 

[paulmd]

Would an Acer

Thanks Wesley, I've got a much better understanding of it now.
Its reporting 4 KB clusters. I assume thats a default setting when you use
NTFS instead of fat32/16?

Any idea on the "overflow" query? He's using the laptop on the original
settings it came with. But I assumed it was standard notebook set up to
target "My Documents" to D:\ when the drive is partitioned. I suppose on
first use he may have been given a choice of saving to C:\ or D:\ ?

)

It will not automatically "overflow" it'll tell you you're out of space.

 

[Wesley Vogel]

Its reporting 4 KB clusters. I assume thats a default setting when you use

NTFS instead of fat32/16?

Yes. 4096 bytes (4KB) is the default cluster size for 2049MB and larger
drives. As if anyone has a drive smaller than that. ;-)

The Default Cluster Size for the NTFS and FAT File Systems
http://support.microsoft.com/kb/314878

4KB is the best cluster size in NTFS for overall performance.

Any idea on the "overflow" query?

Nope, the "Low Disk Space" message is the only thing that is automatic.

When a Windows XP-based computer is running low on disk space, you receive a
"Low Disk Space" message that, when clicked, starts the Disk Cleanup Wizard.
This article describes the conditions in which you receive the "Low Disk
Space" message.

Description of the Low Disk Space Notification in Windows XP
http://support.microsoft.com/kb/285107

--
Hope this helps. Let us know.

Wes
MS-MVP Windows Shell/User

In

 

[Spikey]

Nope, the "Low Disk Space" message is the only thing that is automatic.

When a Windows XP-based computer is running low on disk space, you receive
a
"Low Disk Space" message that, when clicked, starts the Disk Cleanup
Wizard.
This article describes the conditions in which you receive the "Low Disk
Space" message.

He must have been getting warning messages for some time. Ive taken off
some older unused game programs and thats freed up quite a bit of space.

He was also getting periods of hard drive activity when things were freezing
momentarily on the screen. A dvd film was apparently scratched badly during
one of these episodes? Could low disk space have caused this??

Thanks again for the helpful articles. I'm getting a better understanding
of the subject.

)

 

[Wesley Vogel]

Hi Spikey,

He was also getting periods of hard drive activity when things were
freezing momentarily on the screen.

Hard drive activity could be caused by any number of things.

Prefetch doing some defragging; called ProcessIdleTasks or Optimize hard
disk when idle.

Optimize hard disk when idle allows Windows to rearrange files on the hard
disk when the computer is not in use to improve performance.

The WMI Performance Adapter Service (wmiapsrv.exe), for example, will run
and fill %windir%\PCHealth\HelpCtr\DataColl with System History info that
can be viewed in System Information (msinfo32.exe).

And other Windows housekeeping chores.

Viruses or other malware being busy sending E-mails to infect all of his
friends machines.

A dvd film was apparently scratched
badly during one of these episodes? Could low disk space have caused
this??

I have no idea, but it sounds unlikely.

UPDATE your antivirus software and run a full system scan.

UPDATE whatever anti-spyware applications that you have and run a full
system scan with each one.

You might want to start in Safe Mode to run your antivirus and anti-spyware
software.

Running a full system antivirus scan or anti-spyware scan in Safe Mode can
be a good idea. Some viruses and other malware like to conceal themselves
in areas Windows protects while using them. Safe mode will prevent those
applications access and therefore unprotect the viruses or other malware
allowing for easier removal.

How to start Windows in Safe Mode Windows XP
http://www.bleepingcomputer.com/forums/index.php?showtutorial=61#winxo

--
Hope this helps. Let us know.

Wes
MS-MVP Windows Shell/User

In

 

[Spikey]

Hi Spikey,


Hard drive activity could be caused by any number of things.

Prefetch doing some defragging; called ProcessIdleTasks or Optimize hard
disk when idle.

Optimize hard disk when idle allows Windows to rearrange files on the hard
disk when the computer is not in use to improve performance.

The WMI Performance Adapter Service (wmiapsrv.exe), for example, will run
and fill %windir%\PCHealth\HelpCtr\DataColl with System History info that
can be viewed in System Information (msinfo32.exe).

And other Windows housekeeping chores.

Viruses or other malware being busy sending E-mails to infect all of his
friends machines.

I got it up to date with AVg, spybot and Adaware and did full scans both in
safe and normal mode (with show hidden files) before I started the back up
procedure.

I'm looking into housekeeping settings now.

)

 

[Spikey]

The noise wasnt his hard drive its the fans. His laptop management settings
have an option to have fans on or "on demand". I had wondered why it was
getting very hot (my vaio only gets slightly warm) the last time I used it.
I think what is happening is that the fans cut in on full or extra power and
temporarily are diverting the power. I've put them back to the always on
setting for now.

)

 

[Wesley Vogel]

Some times it can be hard to determine exactly what the noise actually is.

I have an old machine and the fan runs all of the time so I can tell for
sure when the hard drive thrashes. Think of an International Harvester
(Binder) threshing machine. ;-) Keep having fun.

--
Hope this helps. Let us know.

Wes
MS-MVP Windows Shell/User

In