4700 Backup/Restore SD

From Technologic Systems Manuals

If backing up on a separate workstation, keep in mind windows does not have direct block device support needed to write these images. You will also need to determine the SD card device. You can usually find this in the output of 'dmesg' after inserting the SD card and you will typically see something like '/dev/sdb' as the block device and '/dev/sdb1' for the first partition. On some newer kernels you will see '/dev/mmcblk0' as the block device and '/dev/mmcblkop1' for the first partition. For these examples I will use the '/dev/mmcblk0' format.

If you are backing up directly on the board you will likely need to use some kind of offboard storage like a thumbdrive or external hard drive. Make sure you have any nbd devices unmounted before trying to restore new ones.

You can find the latest SD card image here. Make sure you decompress the image first before writing.

Note: Not all SD cards are created equally, over time they tend to shrink in size due to automatic retiring of bad blocks. All of Technologic System's images are 10% smaller than the target disc size. We STRONGLY recommend following that same practice on any mass-replicated images.

From Workstation


Backup

Entire SD card

dd if=/dev/mmcblk0 of=/path/to/backup.dd bs=4M
Note: Not all SD cards are created equally, over time they tend to shrink in size due to automatic retiring of bad blocks. All of Technologic System's images are 10% smaller than the target disc size. We STRONGLY recommend following that same practice on any mass-replicated images.

Kernel

dd if=/dev/mmcblk0p2 of=/path/to/zImage bs=4M

Initrd

dd if=/dev/mmcblk0p3 of=/path/to/initrd bs=4M

Restore

Entire SD card

dd if=/path/to/backup.dd of=/dev/mmcblk0 bs=4M

Kernel

dd if=/path/to/zImage bs=4M of=/dev/mmcblk0p2

Initrd

dd if=/initrd bs=4M of=/dev/mmcblk0p3

From SBC


Backup

Entire card

dd if=/dev/mmcblk0 of=/path/to/backup.dd bs=4M

Kernel

dd if=/dev/mmcblk0p2 of=/path/to/backup.dd

Initrd

dd if=/dev/mmcblk0p3 of=/path/to/backup.dd

Restore

The entire card from SBC

dd if=/path/to/2GB-mSD-4700-latest.dd of=/dev/mmcblk0 bs=4M

Kernel

dd if=/mnt/root/zImage of=/dev/mmcblk0p2

Initrd

dd if=/mnt/root/initrd of=/dev/mmcblk0p3

Expected Partition Layout

Partition Contents
1 FAT32 (empty)
2 kernel binary (0xda)
3 initrd (0xda)
4 Debian root filesystem (EXT3)