Cassandraona pi why

Cassandra on a Raspberry Pi.

Why ?

Who Am I ?Andy Cobley

School of Computing

University of Dundee

Twitter: @andycobley

Whats a Raspberry Pi ?

Single chip Linux computer

500 Meg ram

Boots off an SD card

Ethernet port

Pi with pound coin

Here’s oneAnd there is one running in the street area

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

CassandraCan handle very distributed sites

Data can be in any data center, anywhere.

Typically runs on “consumer class” hardware

The Bad NewsCassandra 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 !

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

And then there’s Java!

Oracle Java vs OpenJDK

And RaspbianRaspbian is Debian for the PI

Uses the Hard floating point accelerator

Much faster than Debian

Oracle JDK won’t run on it !

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:

So, have a 64 node computer

for £2000

University of Southhampton

Pi is for teachingSo 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

Pi is discoveryCassandra wouldn’t run on a PI

It does now.

Running it on a Pi shook out some Cassandra bugs

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

ThanksData 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