An academic paper comparing the relative performance of five personal cloud service options has been published by Idilio Drago, Herman Slatman, and Aiko Pras of the University of Twente at Enschede, Netherlands, with Enrico Bocchi and Marco Mellia, at the Polytechnic University of Turin, Italy.
The researchers applied their analysis methodology to five of the most popular Cloud services, assessing their respective system architectures and feature sets, and measuring their relative performance executing a series of benchmarks. They say their results show no clear winner, with all of the services examined suffering from some limitations or having potential for improvement, but some clear distinctions did present themselves. The co-authors observe that in some instances, uploading of the same file set can take seven times longer, and occupy twice as much capacity.
The benchmarking tool and measurements used in their analyses are available at the SimpleWeb trace repository.
The researchers note that many people are are using these services to save personal files, synchronize content on multiple devices and share content with others easily, with the consequent demand drawing more providers to enter the Cloud storage market. Drago et al. observe that services like Dropbox, SkyDrive and Google Drive are becoming pervasive in peoples’ routine, and since these applications are data-intensive their increasing usage now accounts for a significant share of Internet traffic.
Drago and his co-authors say the goal of their paper is twofold. Firstly, they investigate how five different providers tackle the problem of synchronizing users’ files, applying their methodology in order to reveal differences in client software, synchronization protocols and data center placement.
Secondly, they investigate the consequences of such designs on performance by running a series of benchmarks. They note that their results reveal interesting insights, such as unexpected drops in performance in common scenarios because of both the lack of client capabilities and architectural differences in the services, and that, overall, the lessons learned provide useful guidelines to improve personal Cloud storage services.
The researchers conclude that of the five personal Cloud storage services studied, Dropbox implements most of the checked capabilities, and its sophisticated client clearly boosts performance, although there is still potential for some protocol tweaks to reduce network overhead.
On the other extreme, they found that Cloud Drive’s bandwidth wastage is an order of magnitude higher than with other services, and its lack of client capabilities results in performance bottlenecks. They further observe that SkyDrive shows some performance limitations, while Wuala generally performs well, and more importantly deploys client side encryption which doesn’t seem to affect Wuala’s synchronization performance. They also observe that network latency is still an important limitation for U.S. centric services, such as Dropbox and SkyDrive, while services deploying data centers nearer to their test location, such as Wuala, therefore have an advantage. They report that Google Drive uses a different approach that results in a mixed picture; it enjoys the benefits of using Google’s capillary infrastructure and private backbone, which reduce network latency and speed up the system, but the service’s protocols and client features limit performance, especially when multiple files are in play.
The paper can be downloaded in PDF format at ewi1438.ewi.utwente.nl (pdf).