An analysis of Facebook photo caching

Qi Huang, Ken Birman, Robbert Van Renesse, Wyatt Lloyd, Sanjeev Kumar, Harry C. Li

Research output: Chapter in Book/Report/Conference proceedingConference contribution

173 Scopus citations


This paper examines the workload of Facebook's photo-serving stack and the effectiveness of the many layers of caching it employs. Facebook's image-management infrastructure is complex and geographically distributed. It includes browser caches on end-user systems, Edge Caches at ∼20 PoPs, an Origin Cache, and for some kinds of images, additional caching via Akamai. The underlying image storage layer is widely distributed, and includes multiple data centers. We instrumented every Facebook-controlled layer of the stack and sampled the resulting event stream to obtain traces covering over 77 million requests for more than 1 million unique photos. This permits us to study traffic patterns, cache access patterns, geolocation of clients and servers, and to explore correlation between properties of the content and accesses. Our results (1) quantify the overall traffic percentages served by different layers: 65.5% browser cache, 20.0% Edge Cache, 4.6% Origin Cache, and 9.9% Backend storage, (2) reveal that a significant portion of photo requests are routed to remote PoPs and data centers as a consequence both of load-balancing and peering policy, (3) demonstrate the potential performance benefits of coordinating Edge Caches and adopting S4LRU eviction algorithms at both Edge and Origin layers, and (4) show that the popularity of photos is highly dependent on content age and conditionally dependent on the social-networking metrics we considered.

Original languageEnglish (US)
Title of host publicationSOSP 2013 - Proceedings of the 24th ACM Symposium on Operating Systems Principles
Number of pages15
StatePublished - 2013
Event24th ACM Symposium on Operating Systems Principles, SOSP 2013 - Farmington, PA, United States
Duration: Nov 3 2013Nov 6 2013

Publication series

NameSOSP 2013 - Proceedings of the 24th ACM Symposium on Operating Systems Principles


Other24th ACM Symposium on Operating Systems Principles, SOSP 2013
Country/TerritoryUnited States
CityFarmington, PA

All Science Journal Classification (ASJC) codes

  • Software


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