Why are the free space and available space not the same in system monitor?

Question

Why are the free space and available space for the / and /home partitions not the same in system monitor? But the two are the same for the other two partitions?

In particular, my / and /home partitions are running low, and I wonder why I can't use all the free space.

Thanks.

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possible duplicate of df -h shows incorrect free space – muru Oct 18 '14 at 01:01 — muru, Oct 18 '14 at 01:01
Not going to accept one of the answers? – Feb 14 '18 at 12:16 — , Feb 14 '18 at 12:16

score 3 · Answer 1 · answered Oct 18 '14 at 01:04

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After some googling I found this post on Launchpad stating the following (first comment):

The ext3 filesystem reserves an amount of the total space for root. If some user (or daemon) fills the disk then a login couldn't be possible anymore. So even root couldn't login anymore to fix it. Therefore ext3 reserves an amount of 5% (default) of the filesystem for the root user to prevent it (it doesn't work if root fills the disk).

Available space is now the total free space including the reserved space for root. Free space is the free space that you as a user can fill :)

It is possible to change this with tune2fs (PLEASE consult the manpage before using this tool).

answered Oct 18 '14 at 01:04

Justgivemeaname

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I see @Sparhawk beat me to it, linking the same page. :P – Justgivemeaname Oct 18 '14 at 01:04
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Technically I beat both of you. :D This is an old question posed differently. – muru Oct 18 '14 at 01:06
@muru: Technically, I didn't see your post, but you're right! :P – Justgivemeaname Oct 18 '14 at 01:08
@Justgivemeaname +1 Google-fu FTW. :) (Also, I didn't get a notification, perhaps because I hadn't posted a comment here before.) – Sparhawk Oct 18 '14 at 01:16
@muru Please type more slowly. :p (I also think it's a slightly different question, although marking it as a dupe directs people to the correct answer, so meh.) – Sparhawk Oct 18 '14 at 01:17

score 2 · Answer 2 · answered Oct 18 '14 at 01:02

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According to this page, the system reserves 5% for root. For / in your screenshot, 5% of 20.2 GiB is 1.01 GiB, which is about the discrepancy.

answered Oct 18 '14 at 01:02

Sparhawk

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Same thing for /home. 5% of 26.9 is 1.345, which works out about right. Now, I'm hoping you don't ask me about the other two partitions. :) (I think root might only limit it for Linux file systems.) – Sparhawk Oct 18 '14 at 01:21

Why are the free space and available space not the same in system monitor?

2 Answers2