[SATLUG] read only usb fs

Mark Mayfield mark at kandm-solutions.com
Sat Sep 10 17:32:49 CDT 2011


I would do a back up and try dd

as root or with sudo (try both tab positions)
dd if=/dev/zero bs=1k of=/dev/sdb

if dd can't write to it I'd scrap it

On Sat, 2011-09-10 at 17:17 -0500, Borries Demeler wrote:
> > 
> > sometimes vfat partitions will get automounted with defaults. By default
> > vfat has a mask that makes it read only. if this is the case you need to
> > mount it with the option umask=0000.
> > mount -t vfat /dev/??? /mount/point -o umask=0000
> > 
> > after that you should be able to write to it
> 
> No go:
> 
> mount -t vfat /dev/sdb1 /mnt -o umask=0000
> mount: block device /dev/sdb1 is write-protected, mounting read-only
> 
> It doesn't matter which position the read protection tab is in, it
> will not change the result.
> 
> Trying to force r/w doesn't work either:
> 
> mount  -rw /dev/sdb1 /mnt -o umask=0000
> mount: block device /dev/sdb1 is write-protected but explicit `-w' flag given
> 
> stumped...
> 
> -b.
> > 
> > On Sat, 2011-09-10 at 16:08 -0500, Borries Demeler wrote:
> > > When I try to mount/fdisk or otherwise write to 4 GB SD flash memory
> > > from my Canon camera I get an error message that the USB drive 
> > > cannot be written to or the partition table cannot be changed.
> > > 
> > > There is a "lock" tab on the SD card, but neither position makes
> > > a difference. I suspect the Canon camera writes some sort of
> > > protection onto this card, so I am wondering how I can circumvent
> > > this write protection.
> > > 
> > > It looks like a generic brand of SD card that came with the 
> > > camera.
> > > 
> > > Any ideas on how to make this writable?
> > > 
> > > -Borries
> > 
> > -- 
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