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by takeda 2340 days ago
Ext4 reserves space that can be used only by root, it is so system services can continue to work when users take all the space. It doesn't have issues like this if you exhaust all of that space.

In ZFS and I'm sure in btrfs you can set up quotas and reserved space, globally and or user, but by default it is set to 0. I actually set my quota to 80% because apparently if you fill ZFS more it causes heavy fragmentation.
1 comments
paulddraper 2340 days ago
You're 100% correct; ext4 reserves this for a different purpose. I'm just saying it's not a entirely novel idea (albeit for a different reason).
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kasabali 2340 days ago
Ext4 reserved space also helps with fragmentation.

To be more specific, reserved space on ext3 helps the fs so that it can be more flexible during allocation and avoid fragmentation.

Ext4 has delayed allocation mount option for that purpose so reserved space is not as much important for that but it'd still help if you turn off delayed allocations.

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