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A First Look at Problems in the Cloud

A First Look at Problems in the Cloud. Theophilus Benson Sambit Sahu Aditya Akella Anees Shaikh. Cloud Computing. self-service. New delivery and consumption model for IT several service models emerging: infrastructure, platform, SaaS Infrastructure-as-a-Service

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A First Look at Problems in the Cloud

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  1. A First Look at Problems in the Cloud Theophilus Benson Sambit Sahu Aditya Akella Anees Shaikh

  2. Cloud Computing self-service • New delivery and consumption model for IT • several service models emerging: infrastructure, platform, SaaS • Infrastructure-as-a-Service • easily acquire and release virtual servers, storage, bandwidth • no set up cost for users and on-demand usage model • Provider manages the virtual infrastructure resources • New model = new challenges for problem diagnosis • virtualized and abstracted resources • limited visibility into the infrastructure layer locationindependence usage-basedpricing on-demandconsumption rapid elasticity What is required to support problem determination in the cloud environment

  3. Problems in the Cloud • Our objective: develop an understanding of the nature of problems experienced by customers of an IaaS cloud • Understand the types of problems arising in deployment and operation • how do these change over time (longitudinal study) • How users go about solving their problems today • which problems require more help from cloud providers • which problems are persistently difficult to solve • Develop a preliminary characterization of the forum-based cloud support model • see paper for details identify useful mechanisms and best practices forefficient problem resolution in the cloud

  4. Data-driven approach • Study actual user problems and experiences • based on open support forum of a large IaaS Cloud provider • 3 years of message threads • August 2006 through December 2009 • 9,575 reported problems (threads) • Too many for manual classification • Each thread consists of a number of related forum postings • Free text problem symptoms and suggested solutions • Need to impose structure for automated grouping • User id and timestamps • Text analytics to classify reported problems • IR techniques to group problems into clusters • 91% of problems mapped to 20 clusters Problem Description Timestamp User Id/Name Debugging Suggestion 1 Message Body …. Debugging Suggestion N Problem Root cause

  5. Observed problem taxonomy ImageManagement Connectivity Performance VirtualInfrastructure Application Imagebundling Generalconnectivity Instance notresponding Attach/detachvirtual storage Email serversetup Email serversetup Storage and imagemigration Firewall Instance stuckin terminating Virtual loadbalancer Windowslicensing Update/installkernel in img Connecting toapplications Storageperformance DNS andvirtual IP LAMP setup API errors(javaexceptions) Miscconnectivity Connectionperformance Linux SSH key-pair Miscbundling

  6. Size of the Different Classes • Roughly even split across 1st 4 classes • Fewer application problems fewer (typically out of scope for IaaS)

  7. Evolution of Problem Classes • Virtualization grows: release of new features • E.g 3st Quarter 2008: virtual storage • Users unfamiliar with new feature • Maintenance shrinks: release of new tools • E.g 1st Quarter 2007: image manipulation feature • Improves on existing techniques • Connectivity remains stable

  8. Problem Difficulty • Users consult operators for difficult problems • Operators involvement needed for 20-65% of the threads • Performance & virtualization requires the most intervention • Performance: virtualization abstracts away details needed to debug • Virtualization: user can’t change state of provider’s infrastructure

  9. Evolution of Problem Difficulty • Over time less help is needed from the operators • Forum builds up a DB of solutions • In a few cases users still need help from the operators • Resource abstraction limits user control/visibility • The virtualization class is the exception • New features are added: users need help understanding them

  10. Observations Summary • Large fraction of problems solved through self-diagnosis by users • but for some problem classes, significant number require operator involvement • Limited user visibility causes more guesswork and operator involvement • difficult to determine root cause of instance unreachable, unresponsive, etc. • Additional user control for some services could streamline resolution • e.g., inspect or change storage volume state • New features often introduce new problems • proactive release of companion debugging tools

  11. Some Research Issues • How much information to expose to users? • Protect provider infrastructure details • Expose only information relevant to user • Reduce collection/storage overhead • Securing additional user controls • Multitenancy complications • Preventing misuse at the infrastructure level • Making the controls scalable

  12. Conclusion • Empirical study of problems in large provider • Discovered 5 class of problems • Most persistent problems: virtualization & performance • Problems become less difficult as the forum builds up a database of solutions • Suggestion for more effective resolution • Expose more information • Develop specific debug tools for new release

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