Browsing by Subject "Dropbox"

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    Measurement and Enhancement of Peer-to-Peer based File Synchronization with Cloud Assistance
    (2015-07) Pallelra, Ranga Reddy
    Recent years have witnessed the rising popularity of file synchronization systems. Powered by rich datacenter resources, such commercial products as Dropbox and Google Drive not only provide conventional file hosting but also enable file synchronization with multi-party user collaborations. It is however known that their datacenter-based design will limit the system scalability. Peer-to-peer (P2P) based file synchronization, most notably BitTorrent Sync, is therefore widely suggested as a more scalable and efficient alternative. Unfortunately, the framework design and the protocol operation of P2P file synchronization remain vague to the general public. Identifying the exact performance bottlenecks or enabling theoretical and practical optimization is challenging and largely blinding to date. In this thesis, we for the first time investigate the performance of P2P file synchronization in real-world measurement. We deploy BitTorrent Sync on highly-distributed PlanetLab testbed and closely investigate its framework design. Based on our measurements, we find that the P2P file synchronization system can provide very efficient file synchronization, especially for large contents. Different from traditional BitTorrent-like systems, our packet-level analysis also indicates that BitTorrent Sync does not have built-in tit-for-tat protocols. Peers' downloading speed is therefore, independent of their uploading. This modification naturally improves the synchronization efficiency yet also introduces certain fairness issues. For example, our measurement shows that 80% of our peers can obtain a 500MB file within 10 minutes. The remaining 20% users, on the other hand, will suffer from very long synchronization latency; the slowest peers will spend over 30 minutes to download the same file. To mitigate such a problem, we explore the potential to merge the existing P2P-based and cloud-based synchronization systems. The main idea of this hybrid framework is using cloud-based synchronization to accelerate the slower peers in P2P synchronization. Using Dropbox and BitTorrent Sync as a case study, we implement this cloud-assisted P2P synchronization on PlanetLab testbed. The evaluation shows that the cloud-based enhancement can well-address the fairness issues while improving the overall synchronization efficiency by 38%.
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    Towards Reliable User Collaboration over Cloud-based File Synchronization System:Dropbox as a Case Study
    (2016-07) Bommana, Bharath Kumar
    Recent advances in cloud technology have turned the idea of Cloud Storage into a reality. Over the past few years, cloud-based file storage/synchronization systems such as Dropbox, Google Drive and One Drive, have gained tremendous success among Internet users. The cloud storage systems, most notably Dropbox, not only provide reliable file storage but also enable effective file synchronization with diverse user collaborations. It is thus interesting to explore if this cloud-based file storage system can provide reliable collaboration service for the users. In this thesis, we, for the first time, collect samples of content shared on Dropbox and analyze it. We then take our first step to understand the reliable user collaboration over cloud-based file storage systems using the popular Dropbox as a case study. Our observations indicate that users' updates would be discarded without any warning in a classic collaborative file editing session on Dropbox like file storage systems. In particular, to ensure a reliable service, the users need to wait for over 40 seconds between two updates when their uploading capacity is lower than 100 KBytes/sec. This already exceeds the auto-saving interval of many real world applications and severely hinders the system applicability. We further investigate the root causes of this phenomenon and find that such a problem is due to the three-layer design(i.e. user client, cloud virtual machines and cloud storage) of cloud storage systems. To address this problem of losing updates in multi-user collaborative file editing session, we propose an enhancement to the system that keeps track of and saves all the user updates locally and provides the opportunity for the recovery of any historical updates. Our proposed enhancement ensures that none of the user updates will be lost during a file editing session irrespective of the time interval between the updates and thereby making Dropbox user collaboration more resilient and less prone to potential data loss.