[Server-devel] [XSCE] "Raspbian reserves 4% of all disk space"

Samuel Greenfeld samuel at greenfeld.org
Sat Aug 19 22:42:38 EDT 2017

The default threshold probably was 5%, and intentional.

This buffer is meant to allow the root user to use & recover the system if
it is nearly full.  So if this file system has any system purpose and is
not purely for the digital library, you probably want the 5% there.

It also allows the filesystem to have some breathing room for
defragmentation as well as not fragmenting files in the first place.

On Sat, Aug 19, 2017 at 9:16 PM, Adam Holt <holt at laptop.org> wrote:

> ...for exactly what is unclear, on headless RPi's in remote areas
> especially.  Does someone know more about how this reserve disk threshold
> works?  Can it possibly help an untrained operator, in a highly offline
> community, when SD-card-as-primary-disk hits that threshold?
> Certainly WordPress, X Windows (and no doubt others) silently fail upon
> reaching this threshold, rendering the entire system useless, from the
> perspective of a low-skill owner-operator (as is the most common case in
> the developing world).
> So huge thanks to Tim Moody (with George Hunt's assistance) who changed
> this threshold from 4% to 1% as follows:
>    tune2fs -m 1 /dev/mmcblk0p2
> As can be viewed with the "du" (disk usage) command.  The challenge is
> that SD-based digital libraries are Almost Always nearly full, by design,
> when remote educators ask (and deserve) all the best possible materials.
> Nor do we want to discourage constructionist activities that will
> occasionally gobble up a bit of SD/disk!
> So More Generally: how exactly might this 4% threshold (pick your favorite
> percentage, no matter) materially help remote owner-operators, not steeped
> in Linux Skillz?  As so many things start failing together when Raspbian SD
> card "disks" reach that reserve threshold — such that most remote/offline
> educators and owner-operators will simply stop using their RPi3 digital
> library at that point — particularly if it's headless :(
> Suggestions from anyone?!
> *In principle a http://en.wikipedia.org/wiki/Distant_Early_Warning_Line
> <http://en.wikipedia.org/wiki/Distant_Early_Warning_Line> saves lives, but
> if Raspbian/Internet-in-a-Box/Etc do not have a GUI-or-similar alert to
> signal approaching disk-full danger & facilitate the needed "disk" cleanup,
> is this counterproductive, worst case perhaps creating a false sense of
> security among implementers?*
> *(If so wasting impoverished citizens' prescious SD card funds to no
> benefit, or worse giving them a false sense security around RPi reliability
> alongside implementers?)*
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