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?

duplicates: [Same files have different “size on disk” on new drive](https://superuser.com/q/1432383/241386), [Is exFAT less efficient at utilising disk space than HFS+?](https://superuser.com/q/785129/241386), [Please explain wasted space on an exFAT formatted external hard drive](https://superuser.com/a/657410/241386). The reason is simple: the default cluster size on exFAT is huge — phuclv, Aug 17 '21 at 16:06
Does this answer your question? [Same files have different "size on disk" on new drive](https://superuser.com/questions/1432383/same-files-have-different-size-on-disk-on-new-drive) — phuclv, Aug 17 '21 at 16:06

score 5 · Answer 1 · answered Aug 17 '21 at 13:23

5

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.

answered Aug 17 '21 at 13:23

harrymc

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score 1 · Answer 2 · answered Dec 23 '21 at 12:21

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 ^_^

ext4 vs EXFAT: Storage size difference

2 Answers2