windows propterties file sizes

[ShadowBlade]

whats the difference between "size" and "size on disk" in windows file properties?

 

[ShadowBlade]

bump

 

[Nothinman]

Size is how much data is in the file, size on disk is how much disk space that data is using. Filesystem allocate space for files in clusters of a constant size, on most NTFS filesystems this will be 4K, so if the file isn't an exact multiple of the cluster size there will be wasted space which is usually referred to as slack space. There are a number of tricks used to work around wasting lots of space, for instance on NTFS an extremely small file will be stored directly in the MFT entry so that a full 4K cluster isn't wasted if the file is only a few bytes long.

 

[ShadowBlade]

so the size on disk will basically always be a multiple of 4 and the size will be the actual size

 

[lansalot]

A multiple of 4k if the cluster size is 4k. Cluster size isn't always 4k as the man says.

 

[Nothinman]

so the size on disk will basically always be a multiple of 4 and the size will be the actual size

Or a multiple of 512b or a multiple of 1k or 2k or 4k or 8k or 16k or 32k or 64k, depending on what cluster size is in use.

 

[archcommus]

Sorry to resurrect, but this seems to be one of the few threads on this topic.

According to your explanation, wouldn't Size on disk always be higher than Size? However, when I view the properties of all the contents of my C:\ partition (excluding hidden files), the Size on disk is 10.8 GB, whereas the Size is 14.3 GB. How does that make any sense?

 

[TGS]

Unless it's compressed it should always be. Files never use exactly the cluster size so it would be impossible to have exact the same size or less. I would change you folder options to show all hidden files and try to pull up the volume properties again.

Of course if you had an application that wrote out files to an exact size you could get better disk utilization.

 

[bsobel]

NTFS an extremely small file will be stored directly in the MFT entry so that a full 4K cluster isn't wasted if the file is only a few bytes long.

Well, an additional cluster isn't wasted. The MFT entry itself is still used, and it basically has the slack space within it.