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diff --git a/doc/sd_card.txt b/doc/sd_card.txt new file mode 100644 index 0000000..9cc34d6 --- /dev/null +++ b/doc/sd_card.txt @@ -0,0 +1,42 @@ + +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 |