[Sugar-devel] Hello, was Re: Hack to get a USB/SD to autologin to only "Sugar-desktop on a stick". from a F12-alpha live CD

[Douglas McClendon]

Martin Dengler wrote:
> On Wed, Sep 09, 2009 at 06:48:53AM -0600, Douglas McClendon wrote:
>> Douglas McClendon wrote:
>>> Martin Langhoff wrote:
>>>> On Wed, Sep 9, 2009 at 4:26 AM, Douglas
>>>> McClendon<dmc.sugar at filteredperception.org> wrote:
>>>>> My name is Douglas McClendon, and I created the ZyX-LiveInstaller which appears
>>>>>  on track to becoming part of SoaS.  I also can accept praise and blame for
>>>>> the LiveUSB persistence feature I implemented for fedora a couple years back,
>>>> Good to have you on board! One thing we've found is that the overlay
>>>> fs trick is neat but somewhat fragile. In brief - unclean shutdowns
>>>> and "oops, I pulled out the stick" cases very often leave the USB
>>>> stick unbootable.
>>>>
>>>> Of course, first step is fsck.vfat, but after that, we're completely
>>>> lost. Hints would be more than welcome. Ideally, something smarter can
>>>> be done during the boot itself or otherwise with a "repair" script.
>>> Unfortunately I don't have any easy answers.  As someone who works on NDS 
>> Ok, more hints as various vague theories start percolating through
>> my memory.
> 
> If people care to take advantage of your expertise, I hope they can
> provide the filesystems that have failed as examples.  "overlay is
> fragile" is about the level of FUD, AFAICS.  Nothing better has been
> proposed.  No broken filesystems have been made available.  I don't
> doubt the "some sticks 'broke' when yanked out before fs's were
> sync'ed" reports in and of themselves, but when this meme continues it
> makes potential contributors / onlookers think there is some obvious /
> neglected problem.

As the implementer of the current manifestation of the LiveUSB persistence 
feature I'll be the first to confirm it is reasonable to consider overlay 
exhaustion to be a more annoying feature than it needs to be.  I.e. extremely 
hard to detect and recover from.  If someone wants to pay me a salary to 
improve the situation, I could, but otherwise I have more fun nds/guitar 
related projects to work on.  And there may also be better long term ways 
around it than what I would do.

Beyond that, I can also as mentioned confirm seeing problems with corrupted fat 
filesystems.  Maybe all/most from NDS stuff and not LiveOS stuff.  Can someone 
maybe tell me how I'm not understanding fsck.vfat?  I get into this situation 
where it complains about a relatively small (3-6) set of things, and I try to 
submit to its requests.  But its requests aren't at all as obvious as hitting 
'y' to anyting fsck.ext3 asks of you.  And then, when I run fsck.vfat 
immediately again, it asks the same questions as if it did nothing??????  What 
am I missing?

But off tangent back to what you said- unionfs is certainly an alternative to 
overlays, and it sounds like it may be a part of f13, or 14 or thereabouts. 
And unionfs as opposed to overlay for LiveOS certainly from what I know (but 
not from actual use/experience) does handle the overlay exhaustion scenario 
much more easily than the current devicemapper snapshot alternative.  I of 
course don't like unionfs for reasons of rebootless installation preclusion...


-dmc