Look at Size AND Size on Disk. The difference is called file slack.
Nominal disk size
Binary vs. Decimal Measurements
http://www.pcguide.com/intro/fun/bindec.htm
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
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Hope this helps. Let us know.
Wes
MS-MVP Windows Shell/User
In
