torouter is intended to boot and run from an SD. It could theoretically also
run from an internal microSD card, a USB stick, or an eSATA drive, but
specifying use of the SD card makes support, development, and documentation
easier. The SD card can easily be popped out of the router and reflashed with a
new image.

The SD card should be at least 2GB in size and support reasonable read/write
speeds, so probably a "class 6" quality card.

You really should get a decent card: there can be an order of magnitude
difference in performance between a cheap card and a fast card. 

A quick (but inconclusive?) way to check read and write card performance on a
high-performance machine: 

    $ # unmount the card for read test
    $ hdparm -t /dev/sdb    # iff /dev/sdb is the card
    $ # mount the card for write test
    $ dd count=10 bs=1M if=/dev/urandom of=/mnt/disktest


HOWTO Flash to an SD Card
----------------------------

Insert a 4GB+ SD card into to your dev computer (using an adapter if
necessary). ALL DATA AND PARTITIONS WILL BE DELETED.

Use lsblk to figure out which block device the card is (eg, /dev/sdc).

Copy over the image (eg, binary.img) with the dd utility:

    $ dd if=binary.img of=/dev/sdc bs=1M


Potential Improvements
-------------------------

Block-aligned partitions may give significantly better write performance:

http://linux-howto-guide.blogspot.de/2009/10/increase-usb-flash-drive-write-speed.html
http://www.olpcnews.com/forum/index.php?topic=4993.0