NAND out of space crash

John Gilmore gnu at toad.com
Mon Jul 21 21:54:50 EDT 2008


> They are being innundated with "new" problems caused
> by full disk (but weren't really aware that was the cause.)
> 
> Since fixes in 8.2 won't help them for months, they need
> the short term fix (c).

Mitch added Forth words to delete files from the NAND flash, after
we had similar troubles after Christmas (bug #5744, #5719, #5317):
  
  Changed 7 months ago by wmb at ...

  OFW q2d07c and later have the ability to delete files from the JFFS2
  filesystem, so long as there is at least one empty page for storing
  the deletion node.

    ok dir n:\home\olpc\.sugar\default\data\
    ok rm n:\home\olpc\.sugar\default\data\XXX

  where XXX is the name of the file you want to delete.

[I don't know how often there will be no empty page for the deletion
node - I suspect we'll find out.]

I suggest that OLPC figure out a short list of reasonably large files
that we supply on NAND, but which aren't actually needed by most
students (perhaps a language translation for a language they don't use;
or an activity binary that they can easily reinstall later).  Include
that list along with instructions on how to remove one or more of these
files when they get into this jam.

Of course, getting to Forth requires a normal computer (i.e. a
developer key, which every child is entitled to, but apparently no
children actually get).  You can get developer keys, even from a
crashed XO that won't boot NAND, using a collector key, web access,
and a lot of patience.

Somebody who had the sooper secret OLPC script-signing key could write
a Forth script that field teachers could run on crashed lockdown XO's,
which would put them into Forth and let them type.  (Perhaps if you
believe deeply in making security expensive, it can check to see if
the NAND is more than 95% full, and only let them type if so.  Or it
can provide a menu of files for deletion.  Or it can limit itself in
any number of ways, making it less useful but more quote-unquote safe)

	John




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