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

[Tony Travis]

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.
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