TS-4900 MicroSD Backup/restore

From Technologic Systems Manuals

These instructions assume you have an SD card with one partition. Most SD cards ship this way by default. If the card has had its partition table modified this can be corrected with a tool like 'gparted' or 'fdisk'.

Plug the SD card into a USB reader and connect it to a linux workstation PC. Newer distributions include a utility called 'lsblk' which lists all block devices like a USB SD card reader:

lsblk
 NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
 sdY      8:0    0   400G  0 disk 
 ├─sdY1   8:1    0   398G  0 part /
 ├─sdY2   8:2    0     1K  0 part 
 └─sdY5   8:5    0     2G  0 part [SWAP]
 sr0     11:0    1  1024M  0 rom  
 sdX      8:32   1   3.9G  0 disk 
 ├─sdX1   8:33   1   7.9M  0 part 
 ├─sdX2   8:34   1     2M  0 part 
 ├─sdX3   8:35   1     2M  0 part 
 └─sdX4   8:36   1   3.8G  0 part  

In this case the SD card is 4GB, so sdX is the target device. Note that on your system, sdX will not be a real device, it could be sda, sdb, mmcblk0, etc. Technologic Systems is not responsible for any damages cause by using the improper device node for imaging an SD card.

After plugging in the device after Linux has booted you can use dmesg to print out the kernel log. When the USB drive is added it will append to the end of that file. Try running:

dmesg | tail -n 100
 scsi 54:0:0:0: Direct-Access     Generic  Storage Device   0.00 PQ: 0 ANSI: 2
 sd 54:0:0:0: Attached scsi generic sg2 type 0
 sd 54:0:0:0: [sdX] 3862528 512-byte logical blocks: (3.97 GB/3.84 GiB)

Make sure the partition table is using the MBR scheme and not GPT.

In this case, sdXc is shown as a 3.97GB card. Note that on your system, sdX will not be a real device, it could be sda, sdb, mmcblk0, etc. Technologic Systems is not responsible for any damages cause by using the improper device node for imaging an SD card.

The following commands will reformat the first partition of the SD card, and unpack the latest filesystem on there:

# Verify nothing else has this mounted
sudo umount /dev/sdX1

sudo mkfs.ext3 /dev/sdX1
sudo mkdir /mnt/sd
sudo mount /dev/sdX1 /mnt/sd/
wget ftp://ftp.embeddedarm.com/ts-arm-sbc/ts-7990-linux/distributions/debian/debian-armhf-jessie-latest.tar.bz2

sudo tar --numeric-owner -xf debian-armhf-jessie-latest.tar.bz2 -C /mnt/sd
sudo umount /mnt/sd
sync
Note: The ext4 filesystem can be used instead of ext3, but it may require additional options. U-Boot does not support the 64bit addressing added as the default behavior in recent revisions of mkfs.ext4. If using e2fsprogs 1.43 or newer, the options "-O ^64bit,^metadata_csum" must be used with ext4 for proper compatibility. Older versions of e2fsprogs do not need these options passed nor are they needed for ext3.

Once written, the files on disk can be verified to ensure they are the same as the source files in the archive. Reinsert the disk to flush the block cache completely, then run the following commands:

mount /dev/sdX1 /mnt/sd
cd /mnt/sd/
sudo md5sum --quiet -c md5sums.txt
cd -
umount /mnt/sd
sync

The md5sum command will report what differences there are, if any, and return if it passed or failed.