SD Clean/Linux

This is an add-on section for completely recreating an SD card's filesystem using fdisk and mkfs. This should only be done if formatting does not fix your issue or is not possible for some reason.

This page is for Linux users only. If you are not on Linux, see the Windows and/or Mac pages instead.

Instructions

Before beginning these steps, copy all of your SD card's contents to a folder on your computer.

The commands in this guide are case-sensitive. Enter them exactly as written, or there may be unintended consequences.

1. Make sure your SD card is not inserted
2. Open a terminal window and type watch lsblk
3. Insert the SD card and watch for a new device appearing in lsblk
4. Observe the output for the new device. It should match something like this:

   NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
   mmcblk0     179:0    0 29.7G  0 disk 
   └─mmcblk0p1 179:1    0 29.5G  0 part /run/media/user/FFFF-FFFF
   

5. Take note of the name of the device that now appears. In our example above, it was mmcblk0, but it could show up as sda or sdb, if you use a USB adapter
   • If RO is set to 1, make sure the lock switch is not slid down
6. Hit CTRL + C to exit the menu
7. Type sudo umount /dev/<device name>* (do not replace the *)
8. Type sudo fdisk /dev/<device name>.
9. Enter o, then enter n and go through all the resulting prompts without changing settings.
   • If it asks whether to remove a VFAT signature, choose to remove it.
10. Once you are back at fdisk's main menu, enter t and then enter 0c
11. Enter a and then p - observe the output, and make sure the device is now formatted correctly: :

    Disk /dev/mmcblk0: 29.72 GiB, 31914983424 bytes, 62333952 sectors
    Units: sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disklabel type: dos
    Disk identifier: 0x########
    
    Device                Boot  Start      End  Sectors  Size Id Type
    /dev/<partition name>        8192 62333951 62325760 29.7G  c W95 FAT32 (LBA)
    

12. If there are no issues, enter w - this will save changes and exit the fdisk prompt.
13. Type sudo mkfs.vfat /dev/<partition name> -s 64 to reformat the new partition.
    • If the SD card is over 32GB in size, change 64 to 128
14. Type sudo eject /dev/<device name>, then remove and reinsert the SD card.
15. Copy your data back onto the SD card.