Availability, The Cloud and Everything (version 2, Surge2010)

Availability,the Cloud and

Everything

Joe Williams

Saturday, October 2, 2010

Me

• Joe Williams• Infrastructure Engineer • Cloudant• @williamsjoe• joeandmotorboat.com


• Distributed database built on CouchDB• Real-time Search and Analytics• Sign Up! (Free to 256MB)• cloudant.com• http://github.com/cloudant/bigcouch


http://github.com/cloudant/bigcouch

http://github.com/cloudant/bigcouch

Bias

• Distributed Databases (CouchDB)• Amazon EC2• Chef• Erlang


Availability


Availability

• What is Availability?


Availability


Availability

“System availability refers to the accessibility of system services to users. A system is available if it is

operational for an overwhelming fraction of the time. Unlike reliability, availability is instantaneous.”


Availability

“System reliability refers to the property of tolerating constituent component failures, for the longest time. A

system is perfectly reliable if it never fails.”


Availability

• Reliability * Availability = Dependability


Availability

• Availability & Reliability• Mean time to failures• Mean time to repair• Durability• Fault isolation• Fault tolerance


Availability

• Uptime / Downtime• Perceived• Actual


Availability

• Probabilistic Risk Assessment• Event Tree Analysis• Fault Tree Analysis

Apthorpe (http://www.usenix.org/events/lisa01/tech/apthorpe/apthorpe.ps)


http://www.usenix.org/events/lisa01/tech/apthorpe/apthorpe.ps


The Cloud


The Cloud

“It never gets easier, you just go faster.”- Greg Lemond


The Cloud

• Abstraction• Commoditization• Homogenous• Ephemeral


The Cloud

• Costs• Loss of Control• Single Points of Failure• Network Partitions / Data Locality• Unreliable• Performance


The Cloud

• Benefits• API to everything• Fast and Flexible Resource Mgmt• “Unlimited” Resources


The Cloud

• Bootstrapping• Time and Effort

Adam Jacob and Ezra Zygmuntowicz (http://blip.tv/file/2285124/)


http://blip.tv/file/2285124/

http://blip.tv/file/2285124/

The Cloud

• Nodes are stateless and disposable.


The Cloud

"Clouds are systems ... and with systems, you have to think hard and know how to deal with issues in that environment. The scale is so much bigger, and you don't have the physical control. But we think people should

be optimistic about what we can do here. If we are clever about deploying cloud computing with a clear-eyed notion of what the risk models are, maybe we can actually save the economy through technology."

- Security in the Ether By David Talbot - MIT Technology Review Jan/Feb 2010


What’s Next

• Distributed Systems• Automation• Data Driven Operations


Distributed Systems

Baran (http://www.rand.org/pubs/research_memoranda/RM3420/)


http://www.rand.org/pubs/research_memoranda/RM3420/

http://www.rand.org/pubs/research_memoranda/RM3420/

Distributed Systems

• RAID ain’t as redundant as it used to be.

Leventhal (http://queue.acm.org/detail.cfm?id=1670144)


http://queue.acm.org/detail.cfm?id=1670144


Distributed Systems

• Redundancy• Duplication• Distribution


Distributed Systems

• Alphabet Soup• ACID, CAP, BASE, 2PC, MVCC• Vector Clocks, Eventual Consistency• Dynamo, Paxos, Chandra, Byzantine


Distributed Systems

• CAP == Availability


Distributed Systems

• Erlang• Distributed• Concurrent• Fault Tolerant


Distributed Systems

• Erlang• Supervision Trees


Distributed Systems

• Erlang• Hot Code Upgrades• Distributed Upgrades are HARD


Distributed Systems

• Future Work

• Erlang Supervision Trees

• PRA / FTA / ETA

Apthorpe (http://www.usenix.org/events/lisa01/tech/apthorpe/apthorpe.ps)




Automation


Automation

• Optimal use of the cloud.


Automation

• Frequent deployment.


Automation

• Tools• Chef• Puppet• Cfengine• Bcfg2


Automation

• Erlang + Chef (as of v0.8)• erl_call Provider


Data Driven Operations



“What gets measured, gets managed.”-Peter Drucker



• Instrumentation



• Logging



• Visualization



• Demo!



• Modeling

• Analysis

• Universal Law of Computational Scalability

• Amdahl’s Law



• Modeling isn’t just for capacity planning.

Montagne (http://queue.acm.org/detail.cfm?id=1862187)




The End


Questions?

Joe Williams - @williamsjoe
