Why does the total space of a filesystem not match the drive capacity?

niemer · 12. Juli 2019

I'm confused by why the total space of the filesystems don't match the capacity of the drives, each drive is mapped as a single filesystem with a single partition. See attached, they all show ~1-2% less than the drive capacity, and one of the three 10TB drive reports different than the other two...

Hitman95 · 15. Juli 2019

You have an EXT4 file system, it reserves some disk space for backup blocks. You can see how many blocks are reserved with the command:

Bash

tune2fs -l /dev/partition | grep 'Reserved'

For non-root partitions, you can disable reservations:

Bash

tune2fs -m 0 /dev/partition

https://wiki.archlinux.org/index.php/Ext4#Reserved_blocks
https://ma.ttias.be/change-res…t3-ext4-filesystem-linux/

niemer · 17. Juli 2019

Thanks, I disabled reservations on the data drives, but they are still showing the same totals in the filesystem view.

edit: it looks like the Reserved GDT blocks were not released, any reason to keep those around if these disks are purely for storage with a single partition? If not, what's the best way to free up that space?

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