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How Klout migrated from CDH3 to CDH4 …and survived to tell about it
- 1. How Klout migrated from CDH3 to CDH4 …and survived to tell about it Large Scale Production Engineering Meetup September 19, 2013 Ian Kallen Lead Engineer, Klout © 2013 Klout
- 2. About Klout ● recognizing & rewarding online influence ● major social network activity signals ● Facebook, Twitter, Google+, LinkedIn, 4sq ● billions data points consumed & processed ● pipelines update scores & topics ● hive & oozie driven jobs & workflow © 2013 Klout
- 3. By The Numbers ● 2 TB data intake, 200 TB processed daily ● jobs clusters x 2 (dev/staging + production) ● hbase x 6 (dev/staging + production x 5) ● hbase: 350M req/day, 17K req/sec peak ● jobs, hbase & zookeeper total =~ 350 hosts © 2013 Klout
- 4. ● pipelines instable, slow on cdh3 (v0.20.2) ● HBase performance predictability ● old hive version limited pipeline developers ● cdh3 EOL’d 6/2013 ● cdh4 (v2.0.x) supports NN H/A, impala ● more shiney things Motivations © 2013 Klout
- 5. The Environment ● data center hosted ● I/O subsystems are under our control ● network latencies are under our control ● FAQ: Why not AWS? ● saved millions of dollars last year ● that's a lot of beer money. ● elasticity need is low, but... © 2013 Klout
- 6. ● this is super easy on AWS ● bring up a replacement cluster ● double-write or migrate data to replacement ● tear down old cluster ● have a celebratory drink ● if you have any beer money left Cloud Envy © 2013 Klout
- 7. ● nagios, pager duty for monitoring ● monit for process watchdogging ● jmx+, graphite, gdash+ for metrics ● ubuntu boot images for provisioning ● puppet for configuration management ● … no Cloudera Manager Ops Infra © 2013 Klout
- 8. ● no replacement infra to migrate to ○ so upgrades must be done in place ● Cloudera's prefers Cloudera Manager ○ so we were on our own to devise a plan ● Cloudera helped vet our plan (thanks!) ● confidence building on dev/staging clusters ● lots of rehearsals on VM's, bug reports Making Plans © 2013 Klout
- 9. ● detailed checklists, kanban board ● small test clusters, the dev clusters ● planned SLA miss for prod cluster upgrade ● lined up phone consult availability w/Cloudera ○ we needed it about 10 hours into prod jobs cluster ● nobody died Execution © 2013 Klout
- 10. ● jobs run faster (speculative execution?) ● pipelines are faster ● metrics exposed are improved ● HBase clusters lose block locality in transit ○ fixable ● no animals were harmed in this production Aftermath © 2013 Klout
- 11. ● we had many post-mortems along the way ● lots of engineering time & attention ● sweating the details paid off ● mostly because we’re “power users” of hive ● lessons learned: ○ re-align clusters ○ improve use of vendor tools where possible ■ e.g. Cloudera Manager Retrospect © 2013 Klout
- 12. ● dev/staging + prod clusters x 2 ● better use of HDFS paths & job scheduling ● consolidating zookeeper ensembles ● implementing NameNode H/A ● evaluating Cloudera Manager ● evaluating Impala (maybe) Onward © 2013 Klout
- 13. Klout is hiring awesome people passionate about optimizing for innovation & stability, crunching big data & robust systems If you are a great Hadoop DevOps Engineer Join Us! ian@klout.com Thanks! Gratuitous Recruiting Slide © 2013 Klout