When creating a file system ( mkfs ...) the file system reserves 5% of the space for its own use because, according to man tune2fs:


But with large drives 5% is quite a lot of space.

I have 4x1.5 TB drives for data storage (the OS runs on a separate disk), so the default setting would reserve 300 GB, which is an order of magnitude more than the the entire OS drive.

The reserved space can be tweaked, but what is a reasonable size for a data disk? Can I set it to zero, or could that lead to issues with fragmentation?


I have found the following the answer https://www.redhat.com/archives/ext3-users/2009-January/msg00026.html, from Theodore Tso, an ext4 developer.



  • 1
    Great, thanks. Straight from the horse's mouth, even :) – j-g-faustus Dec 31 '10 at 11:59
  • 1
    Still, is it ok to use %1 as reserved blocks not matter what the system is used for ? – Muhammad Gelbana Nov 20 '13 at 11:34

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