Quote from Lob0426 on August 29, 2011, 21:46
First off you will need a switch that has ports for every device. I would reccomend an 8 port or 16 port switch. Make sure it is stackable in case you decide to have more devices in your "Bramble".
This is a good suggestion- and one of the ones I'd make.
One of the other suggestions is that not all switches are made alike- and not all of the name-brand ones are something you'd want for the spine of a Bramble. "Stackable" is going to be a bit of an issue. Most of the stackable ones are "enterprise" level hardware and just took the price advantage of this for experimentation for people and chucked it out the window. If you've got one of the switches worth messing with, while there'll be a slight penalty for daisy-chaining the switch, you can reliably get away with it- so long as you don't try for a high-availability configuration (most consumer hardware does not have spanning-tree support and you'll just cause a packet storm on your cluster with the loops it can't resolve...).
Keep all cabling as short as possible for the best performance.
Heh... Standard 9' cabling will work as well as 3' stuff. Main reason for the short cabling would be to make it easy to keep "tidy".
You will prbably want to use a regular electronics power supply and so you will need a distribution board for power.
While this isn't as crucial as it sounds, it helps. It's just not something that you have to have as we experiment with bringing up a Bramble for the first time.
One device is going to be your interface to the Bramble.
You will have to decide how you are going to mount them. Since all of the boards have mounting holes at, or near, each corner you could use threaded rod with aluminum or plastic spacers for a vertical stack. You could also mount them individually to a project board with screws and spacers, don't crush the SD card socket. Whichever mounting option you finally choose make sure you can plug video and input devices into each device for troubleshooting.
For the initial work, you could just stack them one on top of each other 4-8 of them to keep it tidy. For a larger design once we get moving, we could mount them spacered onto a thin piece of plywood or onto metal/plastic railings, four at a time or 8 at a time onto the carrier board. From there, you'd stack those groupings, again for tidiness.
your primary device will most likely have an HDD attached so make sure to have a mount for it to.
Considering that you can get up to 32Gb of SDHC, you might not need anything in the head-node other than that. You could do with the smallest realistic SD card size (2Gb?) and then a huge one on the main device. It's not like this is going to, at least initially with things, be doing stuff that would rate more than that sort of storage.