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gparted reports 74GB used and 9.02TiB available (seems reasonable).

df reports 40MB used, but only shows 8.6TiB available (suddenly 425 GiB missing)

Disk Info in the file manager reports similar to df, showing 0 bytes used but only 8.6TiB available

Am I actually losing over 5% of my disk to overhead?

gparted df disk info

Erik Johnson
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  • somehow related : https://unix.stackexchange.com/questions/120311/why-are-there-so-many-different-ways-to-measure-disk-usage – Archemar May 27 '21 at 10:40

1 Answers1

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I found the solution to this over on serverfault - the reserved blocks for root-owned processes by default take 5% of your drive. I lowered this to 0% using tune2fs -m 0 /dev/sdb1 and now I am showing all my free space, as espected.

Erik Johnson
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    5% is probably excessive on modern, multi-terabyte drives, but it's still a good idea to keep some in reserve for root, just in case you need to do any emergency repairs/rescues/mv/etc on the filesystem. I recommend setting it to 1%, not 0%. Or use tune2fs -r to set it to an exact number of reserved blocks, e.g tune2fs -r 100000 for 100,000 blocks – cas May 27 '21 at 05:20
  • Also, the 5% is not just for root, but also to avoid excessive/persistent fragmentation. Whether you need 5% is a separate question, but 0% is bad and can permanently hurt performance if ever completely filled. – LustreOne May 28 '21 at 00:20