[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 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 
homebrew that often/always runs from fat, I can only add to anecdotal evidence 
that fat filesystems on flash sticks seem to often get badly corrupted.  I'd be 
curious whether running from ext2/3/4fs (or something else?) has similar rates 
of failure.  Of course when you do that compatability with other 
systems/devices mostly goes out the window, but I'm pretty sure fedora does 
support that.

 From what I've read recently on the state of SSDs, it sounds like you are in 
some cases at the mercy of the quality of the flash and embedded controller's 
implementation.

Now, you didn't describe the situation with the overlay getting exhausted, 
which is probably as common a nuisance.  Theoretically I can outline a brute 
force solution to folding the overlay back into base given sufficient 
tempspace, but I suppose I'm really hoping that btrfs has some magic awesome 
features in the pipeline that make that obsolete before I get around to writing it.

Sorry, no answer here...  Of course you can go with the --home to a seperate 
partition, and no overlay.  I think that might lower the risk of unbootable, 
but leave the risk of corrupted /home, which probably means not much benefit.

I suppose as sticks get bigger, you can dedicate an entire partition to 
disaster recovery, much as normal notebook systems have.

Dunno....

-dmc