[ubuntu-uk] Missing write-protect tab on Secure Digital SD card causing read-only?

[Andrew Oakley]

I understand that the write-protect tab on SD cards is optional:
http://en.wikipedia.org/wiki/Secure_Digital_card#Optional_write-protect_
tab
 
However, when I use an SD card without a tab (no tab at all) on my Linux
Ubuntu 8.04 LTS server, it mounts it as read-only (ro) and absolutely
refuses to mount read-write (rw) even if the -force option is used. It
will only mount cards as read-write, for cards which have a tab and
where the tab is set to the "unlock" position.
 
On my MS-Windows machine (which I only otherwise use for gaming...
honest) this does not happen. It obeys the spec and mounts as read-write
for cards which have no tab.
 
Is this a known bug in Ubuntu 8.04 LTS, or do I just happen to have
poorly designed card reader hardware that is not obeying the SD spec?
 
Googling produces lots of anecdotes but little firm evidence either way.
 
The card readers are internal 3.5" jobs, so I really don't want to pull
the server apart and swap out the card reader unless I'm reasonably sure
it really is likely to be the hardware. It did only cost a fiver at a
computer fair, though, so cost is not the concern - just my time.
 
Andrew Oakley
Head of Software Development
Higher Education Statistics Agency (HESA)
95 Promenade, Cheltenham, Gloucestershire GL50 1HZ
T 01242 211460  F 01242 211122  W www.hesa.ac.uk
<http://www.hesa.ac.uk/> 
 

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