[Bio-linux-dev] Corruption of persistent filesystem on USB-stick

[Tim Booth]

Hi Tony,

Thanks for the patch.  I'd thought about the 4GB limit in regard to
image size but totally forgot about casper-rw.  I'm surprised to see it
manifest as filesystem corruption without warning though - I'd expect to
see an error during the USB stick creation.

Let me know if it fixes the issues and I'll patch the package.

Cheers,

TIM

On Fri, 2014-02-28 at 12:07 +0000, Tony Travis wrote:
> Hi, Tim.
> 
> I've had problems with filesystem corruption on USB-sticks created from
> your 7.0.9 and 7.1.0 Bio-Linux iso images. At first, I thought it was
> because I used an old USB-stick, but when I did a r/w test of the raw
> device it showed no errors. However, when I tried to use the 'portable'
> VirtualBox to 'virtualise' the 7.1.0 stick it complained about my USB
> "casper-rw" being larger than 4GiB, which is the maximum file size on a
> FAT32 partition - That made me wonder if the filesystem corruption was
> caused by "casper-rw" being larger than 4GiB on an 8GiB USB-stick?
> 
> The maximum 'legal' file size for FAT 32 is:
> 
>   2^32 - 1 = 4294967296 -1 bytes = 4GiB - 1 byte
> 
> On my 8GiB sticks, "bio-linux-usb-maker" creates a "casper-rw" > 4GiB.
> 
> This patch limits the size of "casper-rw" to 4095MiB, which is the
> largest file size that can be stored 'correctly' on the Bio-Linux
> USB-stick FAT32 filesystem. I don't know yet if it will solve the
> "casper-rw" corruption problem or not - I'll let you know after I've
> done some further testing of USB-sticks made from your 7.1.0 iso.
> 
> Bye,
> 
>   Tony.
> 
> --
> Dr. A.J.Travis, University of Aberdeen, Institute of Biological and
> Environmental Sciences, Cruickshank Building, St. Machar Drive, Aberdeen
> AB24 3UU, Scotland, UK. tel +44(0)1224 272700, fax +44 (0)1224 272 396
> http://www.abdn.ac.uk, mailto:tony.travis at abdn.ac.uk, skype:ajtravis
> The University of Aberdeen is a charity registered in Scotland, No SC013683.

-- 
Tim Booth <tbooth at ceh.ac.uk>
NERC Environmental Bioinformatics Centre 

Centre for Ecology and Hydrology
Maclean Bldg, Benson Lane
Crowmarsh Gifford
Wallingford, England
OX10 8BB 

http://nebc.nerc.ac.uk
+44 1491 69 2705