The Seagate Dockstar comes with 256MiB of Flash space. Thus we grant the bootloader Das U-Boot-partition entire 1 MiB of space. And this U-Boot is capable of addressing and executing a kernel located on an external device connected via USB. This give you three choices of where you can install your OS:

• on embedded flash installation
  • no need for further hardware
  • if something breaks, the device becomes hard to gain access to.
  • the Dockstar has no additional buttons, which could be used to trigger the failsafe-mode!
• on an USB-Stick install.on.USB
  • easily accessible by connecting directly to a PC
  • easily replaceable
  • bigger than embedded flash
• on an USB-Harddisk install.on.USB
  • easily accessible by connecting directly to a PC
  • huge capacities
  • unlimited write cycles
    • use a journaling file system for /
    • make ample use of SWAP
    • log to harddisc instead to the 128KiB RAM ringbuffer. Log as much as you like. Make log survive reboot.

That way, you can avoid adopting extroot or kexec on the Dockstar. The second and third option gives you all the lightweight advantages of OpenWrt compared to other GNU/Linux distributions you could run on your Dockstar, but you'll probably want to reconfigure your System, so it makes better use of the less limited space your installation medium provides:

• read basic.understanding to remove TMPFS, and have a real /tmp and a separate /var directory.
• log.overview to make you log daemons log to harddisc rather then into the ringbuffer. Assuming that you have a different router which also runs OpenWrt, you can make this write his Logs to this hard disc, too. Use the config or crond to erase to old logs.
• start to install all sorts of daemons, server- and client-software.

You can of course install a (stable?) OpenWrt version on the embedded flash, and additionally install and configure one on a USB harddrive. The Bootloader is configured in a way, that it will boot from USB if there is one, and from embedded flash if this fails. The small benefit is, that OpenWrt on flash gives you much more possibilities than the original firmware, which you could leave unaltered if you installed on external medium.