[EC2] document how to set up elastic load balancing across Stargate instances
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Key: HBASE-2429
URL: https://issues.apache.org/jira/browse/HBASE-2429
Project: Hadoop HBase
Issue Type: Sub-task
Reporter: Andrew Purtell
Priority: Minor
Previously ELB across Stargate instances was made difficult (impractical?)
because scanner state is not distributed among Stargate instances. I thought
about making scanner state serializable and have multiple stargate instances
retrieve and sync scanner cursors up in Zookeeper but obviously that is
problematic for several reasons:
- Performance
- ZK write loading
- As a basic matter of architecture scanners are not meant to be concurrent
across multiple clients
- The prospect seemed a lot of work
Anyway, today AWS announced ELB now incorporates session affinity:
http://aws.typepad.com/aws/2010/04/new-elastic-load-balancing-feature-sticky-sessions.html
http://docs.amazonwebservices.com/ElasticLoadBalancing/latest/DeveloperGuide/index.html?US_EnableStickySessionsLBCookies.html
So unless there is a failure of the Stargate instance (invaliding the scanner,
but the client can restart on that rare error) ELB will transparently use
cookies to maintain a session between a client and the Stargate instance,
enabling proper function of scanners without further work.
Document this.
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