Properties of folder (XP Home)

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What is the difference between “Size” and “Size on Disk” shown on the properties of a folder?

When I look at the properties of a folder on a Windows98 machine from my Windows XP machine on a LAN, it shows:
Size: 8.18MB
Size on Disk: 17.2MB

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Oh yeah, good topic! I call it “fluff” but it’s wasted space because of the file system. It has to do with something called “cluster sizes” in your file system of the operating system and there’s not too much difference in XP from the older versions. A disk is formatted into 512 byte sectors but for the FAT system, a cluster is a group of sectors and every file occupies at least one CLUSTER. Depending on the OS, type of file system (FAT, FAT32, NTFS) cluster sizes can be as small as 512 bytes but are USUALLY 4K, 8K or 16K. On a hard drive with 8K clusters, you can imagine how much space is “wasted” by files SMALLER than 8K! So, the size reading you see is the “real” size (cumulative) of the files and the size on disk is the total space those files are using up. Did I screw this up, or what?

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bigaldoc,

If I copy this folder from the Win98 machine to the local hard disk of WinXP machine, the properties shows the following:
Size: 8.08MB
Size on disk: 8.25MB

What a difference compared to what was shown on the Win98 machine as I posted before! Is there a way to reduce the Size on Disk of this folder on Win98 machne?

FYI: The Win98 machine was formatted under FAT32 while WinXP machine was formatted under NTFS.

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Dennis, I fear the answer is ‘no’ on this one. NTFS uses smaller cluster sizes than FAT32, being a more efficient file system. I wouldn’t sweat it too awful much though, what with this era of mongo-large hard drives – if you’re pressed for disk space there are other solutions.

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