Help me understand it

Guys, as the title said, help me understand this
.. and don't be afraid to get technical!



How is it possible to have the size of files be larger than the size they are occupying on the disc? Compression?

For clarity, >99% of the data is ISOs. And I had copied the exact data on another drive, formatted in the same way that occupied the same space as the data size. I know sometimes data occupies more physical space than they are but this is the first time I'm seeing less.

 

If you click on the Advanced button in attributes, is 'Compress contents to save disk space' checked?

 

Similarly, it's possible to compress an entire drive/partition.

 

No, compress drive is not selected.

 

Size On Disk includes filesystem allocations, hence the difference.

Actual storage amount needed to save files will always be greater than the file size.

Windows doesn't calculate it accurately with super small sizes though.

 

As _nullptr and Adrynalyne say, it has to do with block allocation. Windows will assign an entire 4096 K block to a file that's actually 1 K in size.

 

Attached is the before and after compression sizes of the same iso image. As you can see, the size on disk is significantly smaller when compressed than the raw (uncompressed) size.

 

Thanks for all the responses guys;

I am aware of this fact, but as you can see I'm not talking about small files here I'm talking about huge files about 8 GB a piece.

Mdonah, my problem is not with files being reported larger, this I understand; it is with files being reported smaller than they should be.
In fact when formatting my storage drives I usually take advantage of the block size and usually make them the largest size since the majority of my files are pretty large. So doing this should minimize fragmentation.

My OS drive, I leave as default.

The ISOs here are cannot be significantly compressed as they contain large video files which may already be in a compressed/optimized format. And as I mentioned before, compression was not selected.

 

It doesn't matter, the concept is the same. I was just mentioning that small files may not be accurate.

If the isos are smaller on disk than actual size, they are compressed. If they are larger, its for the reason I mentioned. There is no other possibility.

it should be noted that you don't have to check any box in the properties to have compression. It can be set at a filesystem level with NTFS.

Show me a screenshot of the file in the folder.

 

Sorry, I deleted them. I was doing some 'house cleaning' and backing up, when I saw this. I deleted the files from that location, and had backed them up to another drive where they are reporting same size on disc as file size.

I also have a couple other ISOs of similar type than those that were deleted on the original drive the screenshot were taken from and they too are reporting correctly. So I believe this means is it not compression at the NTFS filesystem level.