For review: NAND out of space patch.

[John Watlington]

On Jul 22, 2008, at 2:23 PM, Jim Gettys wrote:

> Ah, I like this idea better than the previous I've heard; if we can
> uninstall software or cleanup the journal with human intervention,  
> that
> would be good....  I'm nervous about automatic cleanup schemes....
>                        - Jim

Agreed.   Emiliano was already aware of cjb's patch via devel.
I haven't recommended it to Uruguay, but I did make sure that Fiorella
knew of it as one possible solution for her consideration.

wad

> On Tue, 2008-07-22 at 13:20 -0400, Erik Garrison wrote:
>> On Tue, Jul 22, 2008 at 12:53:37PM -0300, John Watlington wrote:
>>>
>>> On Jul 22, 2008, at 12:06 PM, Chris Ball wrote:
>>>
>>>> Hi,
>>>>
>>>>> Can you walk me through the exact steps that the user would
>>>>> experience if this script was installed?
>>>>
>>>> They wouldn't see anything different, but Journal entries
>>>> corresponding
>>>> to files we chose to delete wouldn't resume properly.
>>>>
>>>>> In terms of which files, I think the oldest (or maybe LRU as they
>>>>> say in caches) would be better than the largest. Can we do that
>>>>> (e.g. delete oldest then iterate until x MBs is free)?
>>>>
>>>> I disagree; I don't think we're filling up with small Write or  
>>>> Paint
>>>> documents, my intuition is that we're filling up with recent large
>>>> downloads and movies.  In the case where the problem is a huge
>>>> download
>>>> the user just made, your scheme results in deleting *everything*.
>>>>
>>>> Since we disagree, maybe best to wait until we have some disk-full
>>>> images back from the field so that we can see what used up all the
>>>> space, before deciding the algorithm.
>>>
>>> I'm getting three images right now.
>>>
>>> One of the machines booted, but wouldn't allow any activities to  
>>> launch
>>> (which since you can't log in on vttys kinda locks down the  
>>> machine).
>>> But I did notice a large number of non-standard activities (e.g.  
>>> Doom).
>>
>> This sounds familiar.  I think several teachers from Uruguay have
>> mentioned on the Sur list that their students love to download  
>> software
>> and have filled up their storage space.  I'll try to find the  
>> reference.
>> I have also heard the same from a contractor in Uruguay who has been
>> involved in distribution (via #olpc-ayuda).
>>
>> Today I am going to test a solution in which we union-mount a  
>> tmpfs over
>> top of a full root filesystem (which is effectively read-only).  This
>> should allow us to boot, but obviously any changes made to the tmpfs
>> during the session will be lost.  Provided we can boot in this  
>> scheme,
>> we should immediately open a dialogue which asks the user to select
>> Activities to delete.
>>
>> I think that such a 'recovery-mode' is ultimately the best we're  
>> going
>> to do to help resolve this issue.  We must provide students a way to
>> manage their systems, and to do so even in a NAND-full state, or the
>> solution to NAND-full will continue to be centralized and costly.   
>> If it
>> is not something that we ship immediately to help resolve the  
>> issue in
>> Uruguay, the current situation demonstrates that it is a worthwhile
>> target for future releasese.
>>
>> Erik
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> -- 
> Jim Gettys <jg at laptop.org>
> One Laptop Per Child
>