Cassandra at Hailo

My talk at Cassandra London on 4th February 2014. Covers how Hailo use Cassandra.

Transcript

1. Cassandra at Hailo David Gardner, Architect at Hailo CASSANDRALONDON2014
2. CASSANDRALONDON2014 5th year!
3. CASSANDRALONDON2014 What is Hailo?
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7. CASSANDRALONDON2014 •  The world’s highest-rated taxi app – over 11,000 five-star reviews •  Over 500,000 registered passengers •  A Hailo hail is accepted around the world every 4 seconds •  Hailo operates in 15 cities on 3 continents from Tokyo to Toronto in nearly 2 years of operation Facts and figures
8. CASSANDRALONDON2014 Why Cassandra?
9. CASSANDRALONDON2014 “NoSQL DBs trade off traditional features to better support new and emerging use cases” Andy Gross, Riak http://www.slideshare.net/argv0/riak-use-cases-dissecting-the-solutions-to-hard-problems
10. CASSANDRALONDON2014 •  More widely used, tested and documented software •  Ad-hoc querying •  Talent pool with direct experience What are we trading off?
11. CASSANDRALONDON2014 •  High availability •  Scalability •  Operational simplicity What do we get back in return?
12. CASSANDRALONDON2014 A history lesson •  Version 1 launched in London in November 2010 2 x PHP/MySQL web apps + 1 x Java/MySQL backend •  Version 1.5 launched in Dublin, then 13 others Transitioning to global Java and PHP services built on C* •  Version 2.0 launched 2013 Global Java/Go services built on C* running on a common platform
13. CASSANDRALONDON2014 Why Cassandra? •  A desire for greater resilience – “become a utility” Cassandra is designed for high availability •  Plans for international expansion around a single consumer app Cassandra is good at global replication •  Expected growth Cassandra scales linearly for both reads and writes •  Prior experience I had experience with Cassandra and could recommend it
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15. CASSANDRALONDON2014 Operational Cluster Stats Cluster ap-southeast-1 us-east-1 eu-west-1 us-east-1 eu-west-1 AWS VPCs with Open VPN links 3 AZs per region m1.xlarge machines 5.4TB storage; 600GB data
16. AZ1 eu-west-1 AZ1 AZ2 AZ2 AZ3 AZ3 AZ1 us-east-1 AZ1 AZ2 AZ2 AZ3 AZ3 AZ1 ap-southeast-1 AZ1 AZ2 AZ2 AZ3 AZ3 CASSANDRALONDON2014
17. CASSANDRALONDON2014 C* all the things Stats Service C* many of the things Enlightenment Time Happiness
18. CASSANDRALONDON2014 “How can you have wrong data model in C* when a CF is basically a hash in a hash” Anonymous Engineer at Hailo
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23. CASSANDRALONDON2014 Lessons learned
24. CASSANDRALONDON2014 There will probably be an experience gap •  Have an advocate - get someone who will sell the vision internally •  Learn the theory - teach each team member the fundamentals •  Make an effort to get everyone on board
25. CASSANDRALONDON2014 Watch out for drift •  Cassandra can often be low maintenance – be pro-active •  Keep enough disk space for compactions •  Spot data model problems before they explode
26. CASSANDRALONDON2014 Conclusions
27. CASSANDRALONDON2014 We like Cassandra •  Solid design •  HA characteristics •  Easy multi-DC setup •  Simplicity of operation
28. CASSANDRALONDON2014 Lessons for successful adoption •  Have an advocate, sell the dream •  Learn the fundamentals, get the best out of Cassandra •  Invest in tools to make life easier •  Keep management in the loop, explain the trade offs
29. CASSANDRALONDON2014 The future •  We will continue to invest in Cassandra as we expand globally •  We will hire people with experience running Cassandra •  We will focus on expanding our reporting facilities •  We aspire to extend our network (1M consumer installs, wallet) beyond cabs •  We will continue to hire the best engineers in London, NYC and Asia
30. CASSANDRALONDON2014 Questions?