SD card partition recovery

Create an image of /dev/sdb called sdb.img

dd if=/dev/sdb of=sdb.img

Mount the dd disk image

Establish sector size. Establish where the partition starts

fdisk -l sdb.img

Calculate the offset

startsector*sectorsize
63*512=32256

Mount the disk image

losetup --offset 32256 /dev/loop0 sdb.img

Fix the partition in the disk image Use the appropriate version of fsck and switches

e.g.  fsck.reiserfs --fix-fixable /dev/loop0

Mount the partition in the disk image (optional)

mount /dev/loop0 /mnt

Restore the disk image to a new physical drive (ensure it is unused and not mounted) Unmount the partition, if mounted

umount /mnt

Unmount the disk image

losetup -d /dev/loop0

Restore the fsck'd disk image

dd if=sdb.img of=/dev/sdb