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windows file size

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18 years 2 days ago #18260 by sose
windows file size was created by sose
In windows, every time I check the size of a file or folder I see

- the actual size and a second result which is 'size on disk' which one is the actual size and what is the difference.

Thanks

sose
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18 years 2 days ago #18262 by Smurf
Replied by Smurf on topic Re: windows file size
This is to do with Clusters and Sectors on your hard drive. Sectors are the smallest portion of the hard drive that you can write to and clusters are a collection of sectors that are addressed in the File Allocation Table (this is an explanation for FAT, NTFS is slightly different but still should explain why you are getting the different sizes).

Anyhow, if you have a sector holding 512Bytes and you have a Cluster of 8 Sectors, you would get a 4K Cluster. This would mean that this is the smallest amount of data that can be stored on the drive.

Therefore, if you have a small text file of 600bytes (1 and a bit sectors), you would see the file size as 600bytes but the space on the disk would still occupy the full 4k because the FAT cannot address the additional space as it can only do the 4K chunks. NTFS works slightly different in that the chunks are smaller (so you get less wasted space if you have smaller files) and the way it references and keeps track of the space (uses a Master File Table instead of the FAT)

Hope it makes sense

Wayne Murphy
Firewall.cx Team Member
www.firewall.cx

Now working for a Security Company called Sec-1 Ltd in the UK, for any
Penetration Testing work visit www.sec-1.com or PM me for details.
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18 years 2 days ago #18263 by puneetvig
Replied by puneetvig on topic Re: windows file size
The 'DiskView Size' column shows the actual size occupied on disk by a folder and all its ... Files and Folders are sorted based on their 'size on disk'


Thanks

See Ya!!!!!! Cheers
Puneet
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