After having a corrupted file system on my SD card due (probably due to unsufficient power supply) I want to make a new filesystem. (e2fsck fails, log below.)

However, any file-related changes on the SD card are magically undone!

• First example: when I mount the SD card, delete some files, the files disappear. When I unmount it and mount it again, the files are there again! Similarly when I modify a file's content, the original content is back after re-mount.


• Second example: when I create a new partition table with fdisk, the old partition table is back in place immediately. (Log below.)


• Third example: while I run dd if=/dev/zero of=/dev/mmcblk0 bs=1M, fdisk reasonably said Disk /dev/mmcblk0 doesn't contain a valid partition table. When dd was done, the old partition table was back again.

I have not locked the SD card physically with the small switch. I don't get any read-only errors. In fact, I don't get any errors at all! dmesg doesn't report anything except that I'm mounting a file system with errors.

The problem also occurred running a Xubuntu live cd (12.10). Unfortunately I don't have access to other computers and/or SD card readers at the moment.

Is that a problem of my computer, my SD card, or am I missing something all the time? Any suggestions what I could try?

e2fsck fails:

$ sudo e2fsck /dev/mmcblk0p2 

e2fsck 1.42.5 (29-Jul-2012)

/dev/mmcblk0p2: recovering journal

Superblock needs_recovery flag is clear, but journal has data.

Run journal anyway<y>? yes

e2fsck: unable to set superblock flags on /dev/mmcblk0p2





/dev/mmcblk0p2: ********** WARNING: Filesystem still has errors **********

Here's the log that shows that fdisk has no effect:

$ sudo fdisk /dev/mmcblk0



Command (m for help): p



Disk /dev/mmcblk0: 31.5 GB, 31460425728 bytes

4 heads, 16 sectors/track, 960096 cylinders, total 61446144 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

Disk identifier: 0x00017b69



        Device Boot      Start         End      Blocks   Id  System

/dev/mmcblk0p1            8192      122879       57344    c  W95 FAT32 (LBA)

/dev/mmcblk0p2          122880    61446143    30661632   83  Linux



Command (m for help): d

Partition number (1-4): 1



Command (m for help): d

Selected partition 2



Command (m for help): p



Disk /dev/mmcblk0: 31.5 GB, 31460425728 bytes

4 heads, 16 sectors/track, 960096 cylinders, total 61446144 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

Disk identifier: 0x00017b69



        Device Boot      Start         End      Blocks   Id  System



Command (m for help): w

The partition table has been altered!



Calling ioctl() to re-read partition table.

Syncing disks.







$ sudo fdisk -l /dev/mmcblk0



Disk /dev/mmcblk0: 31.5 GB, 31460425728 bytes

4 heads, 16 sectors/track, 960096 cylinders, total 61446144 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

Disk identifier: 0x00017b69



        Device Boot      Start         End      Blocks   Id  System

/dev/mmcblk0p1            8192      122879       57344    c  W95 FAT32 (LBA)

/dev/mmcblk0p2          122880    61446143    30661632   83  Linux