1. Cassandra on a
Raspberry Pi. Why ?

2. Who Am I ?
Andy Cobley
School of Computing
University of Dundee
Twitter: @andycobley

3. Whats a Raspberry Pi ?
Single chip Linux computer
500 Meg ram
Boots off an SD card
Ethernet port

4. Pi with pound coin

5. Here’s one
And there is one running in the street area

6. What’s Cassandra ?
NoSQL database
Important thing is it’s disturbed.
Scales and runs best in a cluster
Data is replicated across nodes
Any node, can answer any query

7. Cassandra
Can handle very distributed sites
Data can be in any data center, anywhere.
Typically runs on “consumer class” hardware

8. The Bad News
Cassandra is designed to be fast, fast at writing, now
even faster at reading.
This laptop with one instance of Cassandra will do
12,000 write operations
Raspberry Pi will do 200 !

9. More bad news !
Running a external USB drive is actually worse !
Problem is the USB, the SD card and the Network
card all share the same bus

10. And then there’s Java!
Oracle Java vs OpenJDK

11. And Raspbian
Raspbian is Debian for the PI
Uses the Hard floating point accelerator
Much faster than Debian
Oracle JDK won’t run on it !

13. The Good News !
We’ve forgotten one thing
The Pi cost £25
You can power 4 from USB hub (no need for a power
supply on each one
So:

14. So, have a 64 node
computer for £2000
University of Southhampton

15. Pi is for teaching
So for £200 we get an 8 node Cassandra cluster
It can be reconfigured, blown away, stress tested and
generally abused
We can simulate data racks, data centers and I hope
even long network delays.
Our upcoming MSc in Data Science will use these
clusters

16. Pi is discovery
Cassandra wouldn’t run on a PI
It does now.
Running it on a Pi shook out some Cassandra bugs

17. Pi is for fun !
Most important, this was pure Geeky Fun

18. Thanks
Data Science:
http://www.computing.dundee.ac.uk/study/postgrad/
degreedetails.asp?17
Dundee Developer Day and Big Data
17 November in here
http://dun.dddscotland.co.uk/sessions