Martin Michlmayr
A NSLU2 from the front

How to clone a NSLU2

When you have installed Debian on one Linksys NSLU2, it is relatively easy to clone your installation for a second NSLU2. This pages describes the steps necessary to clone an existing NSLU2.

Before you start, I have to mention one complication: as of Debian 6.0, device names like /dev/sdaX are no longer used in /etc/fstab and UUIDs are used instead. UUIDs are unique IDs that identify a partition. While the use of UUIDs has certain advantages (for example, you can connect more than one disk to your NSLU2 without Linux confusing which disk is which), it makes cloning a NSLU2 harder. There are two ways around this problem:

  1. Convert /etc/fstab to use device names: edit /etc/fstab and replace all UUIDs with /dev/sdaX device names. Then run update-initramfs -u to generate a new ramdisk.
  2. Make sure that the second disk uses the same UUIDs: After formatting a partition with the ext2/3 filesystem, you can set the UUID with tune2fs -U. When creating swap, use mkswap -U to set the UUID.

In the following example, we'll assume that you are using /dev/sdaX device names in /etc/fstab.

In order to clone your NSLU2, start your first NSLU2 and make a copy of the flash content:

cat /dev/mtdblock* > nslu2-backup

Copy the file nslu2-backup to another machine and turn your NSLU2 off. Now connect the USB drive from your first NSLU2 to your PC and make a tar ball of the whole disk (the following examples assume the standard Debian layout):

mount /dev/sda2 /mnt
mount /dev/sda1 /mnt/boot
mount /dev/sda6 /mnt/home
cd /mnt
tar -cjpf ~/nslu2.tar.bz2 .

Now disconnect this drive and connect the drive from the second NSLU2. You have to partition and format the disk. Please see the manual installation of Debian for more information on how to partition and format the disk. Make sure to use exactly the same layout as the first disk. Now format it:

mkfs.ext2 /dev/sdb1
mkfs.ext3 /dev/sdb2
mkfs.ext3 /dev/sdb6
mkswap /dev/sdb5

And mount the disk:

mount /dev/sda2 /mnt
mkdir /mnt/boot /mnt/home
mount /dev/sda1 /mnt/boot
mount /dev/sda6 /mnt/home

Now you can unpack the tar file:

cd /mnt
tar -xjvf ~/nslu2.tar.bz2

You have to make some changes to the disk. Edit /mnt/etc/udev/rules.d/70-persistent-net.rules and replace the existing content with the following line:

SUBSYSTEM=="net", ACTION=="add", DRIVERS=="ixp4xx_eth", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"

This is important because this file will contain the MAC address of your first NSLU2 and is therefore not appropriate for your new NSLU2. The new configuration doesn't specify a MAC and will work with any NSLU2.

Finally unmount the disk:

cd /
umount /mnt/home
umount /mnt/boot
umount /mnt

Connect the new disk to your new NSLU2 and upload the firmware image previously generated (nslu2-backup) with upslug2. Your second NSLU2 should now run Debian as well!