Re: The case of the read-only USB sticks.

[Frank Miles <fpm@u.washington.edu>]

On Sat, 22 Feb 2014 15:40:01 +0100, Hendrik Boom wrote:

> I have a problem with my USB sticks mysteriously becoming read-only.
> 
> I decided to investigate. I bought three identical 8G USB sticks, 
> identical except for colour).  None of them appear have any switches on 
> them.
> 
> The first I used my Linux laptop to write a file into the top-level 
> directory of the first stick:  I mounted it, wrote it, and unmounted it.  
> I handed it to my wife, who was to read it on her Mac.  She told me it 
> failed to even notice there was a USB stick plugged in.  But returned to 
> me, I could mount it and read it.
> 
> I put the second into my Linux laptop, mounted it, listed the top-level 
> directory (it was empty), unmounted it.  I passed it to my wife, who 
> plugged it into her Mac, and it immediately noticed the USB stick and 
> allowed her to look at its contents.  It was, of course, empty.
> 
> I'm running Debian testing on an ASUS netbook.
> 
> Speculation: 
> 
> Now this doesn't tell me anything about how my USB sticks turn read-
> only.  But it does tell me that something weird is happening to them.  
> Perhaps the two OS's have different ieas as to how USB sticks are to be 
> written or read?  Perhaps one of the other machined in the house it 
> writing the in such a was that Linux can't read them?
> 
> What do I need to know to investigate this.
> 
> Has anyone else had problems like this?
> 
> Online all I found was some people on Windows with read-only USB sticks.  
> One of them said that some friend using Linux had "fixed" them.  No one 
> else had any luck.  I have no idea if their experience has any relevance.
> 
> -- hendrik

You said you wrote to the "top level directory".  I'm guessing you were
running as root and wrote to a section that you shouldn't have tampered with.
For example, a drive might appears both as /dev/sdd and /dev/sdd1.  You don't
want to mess with /dev/sdd - loosely speaking, that's just for the partition
table (i.e. use fdisk or one of its kin to alter if necessary).  Read/write/mount
only the /dev/sdd1.

Of course the drive could have failed, but it seems unlikely.

Have you tried to fsck the drive?

HTH--
  -F