
Multi-Datacenter Cassandra on 32 Raspberry Pi’s - zzzqqq
http://www.datastax.com/dev/blog/32-node-raspberry-pi-cassandra-cluster
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sgt
I'd be worried about just switching RPi's off. We recently got a Pi for the
office to run as a dashboard - and after a couple of power cuts it corrupted
the SD card.

Now I'm going to have to set up the system again, and I don't know whether
this is going to happen again. The SD card that got corrupted was a Class 4
Kingston.

Maybe I'll look into a Sandisk (possibly Class 10?) next time. But I am
worried that it's not the SD card's fault, but rather a combination of a
journaling filesystem, an SD card and a sudden power outage.

Edited: Apologies, I realized now that the red button cuts power to the
network switch, not to each individual Pi. But my concerns about the Pi and
power cuts still remain though.

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praseodym
Raspberry Pi's are very susceptible to SD card corruption. And it's hard to
fix: [http://raspberrypi.stackexchange.com/questions/7978/how-
can-...](http://raspberrypi.stackexchange.com/questions/7978/how-can-i-
prevent-my-pis-sd-card-from-getting-corrupted-so-often)

~~~
_pmf_
I had one device that just killed all SD cards on power up. I still don't
fully understand how this is even possible.

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thinkingkong
Is there a video we can see? Hitting the button im imagining the circles
showing some kind of re-sync animation?

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danbruc
Well, if everything works it will be a very boring video, nothing will happen.

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abritishguy
Well I'm assuming when half the pis turn off half of them will go red.

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coreymgilmore
Pretty cool. Would like to see it working (video/timelapse/gif)?

Also, any reason for not making the big red button randomly select a
"datacenter" to take offline?

Idea: transition this into a 3 or 4 datacenter cluster.

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crazypyro
I noticed the mention of FIRST and at the same time, noticed the red/blue
color choice. I'm sure its just a coincidence, but still entertaining. Project
looks awesome.

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smoothpooper
Demoing the multicluster setup and simulating the failure to various people
was the hardest part for me. This will help so much. A video will be nice.

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PanMan
How is the circle of lights set up? What does it show?

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robszumski
The two rings in the middle are from OpsCenter, the admin UI that they
provide. The lights on the outside are from the LED on the Pis I believe.

If you hit the button, I believe one of the rings would turn red but the
cluster would still be able to function.

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fasteo
Picture of the back of that wall !!

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rodvlopes
I see rpis everywhere... Are they self-replicating?

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mkoryak
and here is the link to the "high res" picture of the setup 4000x2000:
[http://www.datastax.com/wp-
content/uploads/2014/08/cluster_c...](http://www.datastax.com/wp-
content/uploads/2014/08/cluster_closeup_final.jpg)

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ribs
Wicked! I want to see a video.

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rjurney
They need a custom designed enclosure with pretty lights.

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yossarian314
Nice

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bfrog
They say it was difficult to get a high performance DB running on a 700mhz
chip with 512Mb of ram. Perhaps its just the wording but that sounds like the
opposite of high performance to me.

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pplante
i think they meant to highlight the high resource requirements.

