I have been filling a hard drive and a couple of backup drives with the family pictures and videos. Once a video goes into the archive, it remains there in a folder correctly labeled with the date. The data collection has grown up to the point where I need a new drive (and new backup drives).

But I wonder why should I leave the reserved blank space linux enforces in the drive, which now is above 50 GB I could fill with more videos. It is easy to do that by invoking the 'cp' command as root.

Since I am not going to do anything else with the drive other than archival purposes, I wonder if filling that reserved space would be a bad practice, in this case, and why. I know I shouldn't do that with the main drive inside the laptop, otherwise the system may become unstable, but what about that external drive holding only archival data?

  • BTW, I would like to know about solutions to store this 2 to 4 TB collection in some kind of cloud solution to make sure it lasts many years. But I cannot add this to the main question.
    – Mephisto
    Mar 4, 2019 at 20:22
  • 1
    webapps.stackexchange.com is a good place to ask about that.
    – K7AAY
    Mar 4, 2019 at 21:39

1 Answer 1


I assume that you are using an ext4 file system: You can modify the size of the reserved space with tune2fs. The following command line reduces the reserved space to 1% (from default 5%).

sudo tune2fs -m 1 /dev/sdxn

where x is the drive letter and n is the partition number (of a partition with an ext file system).

From man tune2fs:

   -m reserved-blocks-percentage
          Set the percentage of the filesystem which may only be allocated
          by  privileged  processes.   Reserving some number of filesystem
          blocks for use by privileged processes is done to avoid filesys‐
          tem  fragmentation,  and  to  allow system daemons, such as sys‐
          logd(8), to continue to function correctly after  non-privileged
          processes  are  prevented  from writing to the filesystem.  Nor‐
          mally, the default percentage of reserved blocks is 5%.

You can reduce the size of the reserved space in a data drive (which is not as critical as a system drive). But as described in the manual, space is reserved to

  • avoid fragmentation (relevant also for a data partition)
  • allow system daemons to continue to function correctly

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