answered PoE single-board cluster?

[IamDotDotDot]

Hello all,

I want to build a single-board cluster for educational reasons, but I just don't want to use raspberry pis. I like the idea of using the ODROID-MC1's, but I think it would be cool to use PoE for it. Now of course, this is not a cost-efficient project, but I also don't want to destroy my fund (about $1700) in the process. I wanted to use 12 mc1 boards. The power needed is 5V/4A, and I need 12 (not including my NAS or master node) of those if I were power these by conventional means (5V 60A 300W Power Supply plus adapters). My question to all of you is: can I use PoE for this project and cut out the power supply, or should I just stick to having that extra hardware and wire chaos. If so, is there a switch that can handle the load these boards need? Can these boards even support PoE? If the PoE is an option but the boards are not, is there another board I could use that DOES have PoE capabilities?

 

Bonus question: Anyone got some cool ideas for a name for this cluster?

[TheBean]

may I know why you do not want to use a raspberi pi?

 

name: eduCluster? ClusterBomb? Pegasus? LinusDropTips? 

 

edit: i dont think you can do 4A with PoE but I might be wrong

Edited October 27, 2019 by Saksham

[IamDotDotDot]

Just now, Saksham said:

may I know why you do not want to use a raspberi pi?

 

name: eduCluster? ClusterBomb? Pegasus? LinusDropTips? 

I want the project to feel special, and I feel like too many people have built Brambles (pi clusters) for the project to have that sort of *wow* factor to it. I had originally wanted to use the Teensy 4.0's but there were way too many hoops to get through for that to be realistic. (here is a link to that forum post https://forum.pjrc.com/threads/57941-A-Beowulf-Cluster-of-Teensy-4-0-s )

 

Also, I might be tempted to skip out on running it headless, and just use a monitor. I know myself well enough to know that if presented with the option, I will take the easy way out.

[brandishwar]

The MC1s don't support PoE directly. There are a few ways to do that, though. You can use PoE splitters at each MC1 with a PoE-capable switch providing the power. But the 802.3af standard (which governs power-over-Ethernet) only supports up to 15W per line. Add in the 48V to 5V voltage conversion, and you're losing a little power in that. 802.3at+, however, supports about 25W, but you're still going to lose some of that to voltage conversion using a splitter. So not really worth it, especially since the splitters are going to add about $20 per unit to the cost.

 

An alternative is off-standard PoE device pairs: an injector on one end, and a splitter on the other. But if you're not going to be too far from the switch, that is overkill. Plus I don't think you're going to find any that will support the wattage you need.

 

You're better off just using a good 5V power supply to power all of these. To allow for overhead, make sure it can supply 60A (5A per board) at 5V.

[IamDotDotDot]

7 minutes ago, brandishwar said:

The MC1s don't support PoE directly. There are a few ways to do that, though. You can use PoE splitters at each MC1 with a PoE-capable switch providing the power. But the 802.3af standard (which governs power-over-Ethernet) only supports up to 15W per line. Add in the 48V to 5V voltage conversion, and you're losing a little power in that. 802.3at+, however, supports about 25W, but you're still going to lose some of that to voltage conversion using a splitter. So not really worth it, especially since the splitters are going to add about $20 per unit to the cost.

 

An alternative is off-standard PoE device pairs: an injector on one end, and a splitter on the other. But if you're not going to be too far from the switch, that is overkill. Plus I don't think you're going to find any that will support the wattage you need.

 

You're better off just using a good 5V power supply to power all of these. To allow for overhead, make sure it can supply 60A (5A per board) at 5V.

Thank you