I have a 3TB HDD. In the properties screen of the HDD, it says that I have used 471.4GB, but when I select all the files in nautilus, it says that 321.0GB is selected. If I only have 321.0GB of files in the HDD, why is it using 471.4GB?
The HDD's partitioning is using GUID and file system being used in EXT4. When I select the HDD using Disk Utility app, I get a warning saying:
WARNING: The partition is misaligned by 3072 bytes.
This may result in very poor performance. Repartitioning is suggested.
Has that got anything to do with the missing 150.4GB?
Best Answer
Files on disk have two sizes: the "apparent size" and the "size on disk". Several reasons can cause a large discrepancy:
I would suggest to use a disk usage tool known to be capable of listing both sizes to see if this is the issue. Try
ncdu
in a terminal and use a to toggle between actual and disk usage.A short demo on internal fragmentation due to a 4KiB block size filesystem using
du
:This means that this 10-byte file is 4086 bytes bigger on disk than it would appear in a listing and is suffering from internal fragmentation.
A short demo on hard links and disk usage shown wrong when listing files (
ls
in this case):