[Techteam] NAND full issue
wmb at laptop.org
Sun Jul 27 13:39:50 EDT 2008
Martin Langhoff wrote:
> On Sat, Jul 26, 2008 at 1:00 PM, Daniel Drake <dsd at laptop.org> wrote:
>> unionfs will involve a kernel change.
> Erik's got a ko to add to the initrd AIUI.
>> Have we considered sorting by date and removing from oldest to new until
>> the threshold is reached? Perhaps excluding starred items.
> Both date and size are flawed -- Greg and Cjb have explored the flaws
> of both approaches on devel at . The best notes on this are from Mitch so
> far - he looked at the FSs and spotted things we can safely delete.
> And we cannot query for starred items without starting the journal,
> which does not start in no-space conditions.
> IMHO, Cjb's script should delete caches and the files various files we
> know are safe to nuke _before_ we even consider user data
The big-ticket item is the contents of ~/.sugar/data . According to
Tomeu in the attached
message, those files are leaks and could be deleted on boot without
In the images that I analyzed, those files represented 50% or more of
the size of /home,
ranging from ~500 to ~800 MB. As a "quick fix", just deleting those
leak files on every
boot would probably reduce the incidence of NAND-full reboot failures by
of magnitude, which should be enough to downgrade the problem from
Ironically, the presence of that leak (which Tomeu claims is fixed in
inoculate the system against NAND fillup from other causes, by
"reserving" space that
can be reclaimed upon reboot.
That suggests a long-term safety strategy:
a) Determine how much free space is needed to ensure that the system can
to a level where filesystem cleanup and maintenance can be performed.
let's say the magic amount is 50 MB.
b) Add a 50 MB space-holder file to the filesystem on the first boot (or
as part of the
initial image). Fill it with incompressible data so it actually
occupies the full space.
c) On each boot, if there is less than 50 MB free, delete the
space-holder file to free
up space, and boot in maintenance mode so the user or a helper can clean
booting in maintenance mode until the free space has increased above
After the cleanup, recreate a space-holder file.
Of course, it is still important to automate as much cleanup as can
safely be performed
without user intervention, but the space-holder approach is still a good
avoid trips to a repair center.
> - Mitch has identified stray CVS directories. These are safe to nuke.
> - /var/cache/yum
> - ~/.sugar/default/logs
> - ~/.sugar/default/gecko/Cache
> - Someone mentioned large support files in eToys.
> Might be worthwhile to nuke large Activities in ~/Activities.
> If not enough space is available, then it makes sense to nuke user data.
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Subject: Re: [Techteam] Files from Uruguay
Date: Thu, 24 Jul 2008 09:25:36 +0200
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