ext4 vs EXFAT: Storage size difference

Question

I have 2 hard drives, one is EXT4 and one is EXFAT. Both are 8TB, and both contain the same files.

However, if I look at the amount of space being used in Gparted on Ubuntu, there is a big difference. Also included screenshots from the File Manager in Ubuntu.

EXT4: There is 154 GB free.

EXFAT: there is 13 GB free.

From the screenshots, it looks like both drives have a allocation unit size / block size of 512 bytes, so I don't think (?) that can explain it (could be wrong though).

What gives?

Answer 1

The EXFAT cluster size is not 512 bytes, which explains the difference.

Microsoft's Default cluster size for NTFS, FAT, and exFAT has this table:

Your cluster size is then 128 KB, while for ext4 this is likely 4 KB bytes.

Answer 2

By any chance you have mostly large files in thd drives? I had similar questions and I suspect it has something to deal with:

• exFAT uses a File Allocation Table with pre-allocation. Meaning files are likely to take up more space than the actual data.
• ext4 on the other hand has delayed allocation and a lot of other goodies that will make it more space efficient.
• the fact that maximum cluster size of exFAT is 32MB while extends in ext4 can be as long as 128MB.

To be honest I'm a little surprised how well Ext4 compared with exFAT ^_^