How to reformat my SD card?

Question

I have a micro SD card (/dev/mmcblk0) with one partition on it (/dev/mmcblk0p1).

There is a btrfs filesystem on it, that won't mount. When I insert it, I get an error message on the desktop, saying:

Error mounting /dev/mmcblk0p1 at /media/franck/mysdcard: Command-line `mount -t "btrfs" -o "uhelper=udisks2,nodev,nosuid" "/dev/mmcblk0p1" "/media/franck/mysdcard"' exited with non-zero exit status 32: mount: wrong fs type, bad option, bad superblock on /dev/mmcblk0p1,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

So I want to erase the disk, re-partition it and reformat to a new fs (probably ext4).

My problem is that I cannot do it. fdisk as well as gparted try to do it, and then fail to read again the partition table:

$ sudo parted /dev/mmcblk0
GNU Parted 2.3
Using /dev/mmcblk0
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) print                                                            
Model: SD SD64G (sd/mmc)
Disk /dev/mmcblk0: 63.4GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type     File system  Flags
 1      16.8MB  62.4GB  62.4GB  primary  btrfs

(parted) rm 1                                                             
(parted) print                                                            
Error: /dev/mmcblk0: unrecognised disk label   

If I remove and re-insert the device, the old partition and fs are still here.

I suspect gvfs is holding a lock on the device, preventing any write on it:

$ sudo lsof /dev/mmcblk0
lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1000/gvfs
  Output information may be incomplete.

So, is there a way to erase my disk ?

Solution

Just zero out the drive and create a new partition table.

Zeroing the Drive:

sudo dd if=/dev/zero of=/dev/mmcblk0

To create a new parition table, simply use GParted or a similar tool.

Comments

[T_S_]

Even that did not work. dd executed just fine (took a while). But when I reinserted the card, the old partition is still there! (maybe the write could not be synced to disk? Maybe the media is broken?

[Kaz Wolfe]

@alci Edited it. Try the updated command.

[T_S_]

Ok, I think the card is definitely broken. I get IO errors whatever I try... Thanks for the tips. Marking this as answer, as it works on other cards and is good to remember.

[Jan]

maybe adding a bs=1M would fasten that thing up a lot? or is that not valid in this case?