Creating and Maintaining Replicas in Unstructured Peer-to-Peer Systems

  • Elias Leontiadis
  • Vassilios V. Dimakopoulos
  • Evaggelia Pitoura
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4128)


In peer-to-peer systems, replication is an important issue as it improves search performance and data availability. It has been shown that optimal replication is attained when the number of replicas per item is proportional to the square root of their popularity. In this paper, we focus on updates in the case of optimal replication. In particular, we propose a new practical strategy for achieving square root replication called pull-then-push replication (PtP). With PtP, after a successful search, the requesting node enters a replicate-push phase where it transmits copies of the item to its neighbors. We show that updating the replicas can be significantly improved through an update-push phase where the node that created the copies propagates any updates it has received using similar parameters as in replicate-push. Our experimental results show that replicate-push coupled with an update-push strategy achieves good replica placement and consistency with small message overhead.


Data Item Replication Strategy Query Rate Consistency Level Message Overhead 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Cohen, E., Shenker, S.: Replication Strategies in Unstructured Peer-to-Peer Networks. In: Proc. ACM SIGCOMM 2002 (2002)Google Scholar
  2. 2.
    Lv, D., Cao, P., Cohen, E., Li, K., Shenker, S.: Search and Replication in Unstructured Peer-to-Peer Networks. In: Proc. ICS 2002, 16th ACM Int’l Conference on Supercomputing, New York, USA (2002)Google Scholar
  3. 3.
    Datta, A., Hauswirth, M., Aberer, K.: Updates in highly unreliable, replicated peer-to-peer systems. In: Proc. of ICDCS 2003, 23rd Int’l Conference on Distributed Computing Systems, Providence, Rhode Island, pp. 76–85 (2003)Google Scholar
  4. 4.
    Dimakopoulos, V.V., Pitoura, E.: Performance analysis of distributed search in open agent system. In: Proc. IPDPS 2003, Int’l Parallel and Distributed Processing Symposium, Nice, France (2003)Google Scholar
  5. 5.
    Leontiadis, E., Dimakopoulos, V.V., Pitoura, E.: Cache Updates in a Peer-to-Peer Network of Mobile Agents. In: Proc. P2P2005, 4th Int’l Conference on Peer to Peer Computing, Zurich, Switzerland, pp. 10–17 (2004)Google Scholar
  6. 6.
    Leontiadis, E., Dimakopoulos, V.V., Pitoura, E.: Creating and Maintaining Replicas in Unstructured Peer-to-Peer Systems. Technical Report TR2006-01, Univ. of Ioannina, Dept. of Computer Science (2006)Google Scholar
  7. 7.
    Srinivasan, R., Liang, C., Ramamritham, K.: Maintaining temporal coherency of virtual data warehouses. In: Proc. RTSS 1998, 19th Real Time Systems Symp., Madrid, Spain (1998)Google Scholar
  8. 8.
    Urgaonkar, B., Ninan, A., Raunak, M., Shenoy, R., Ramamritham, K.: Maintaining mutual consistency for cached web objects. In: Proc. ICDCS 2001, 21st Int’l Conference Distributed Computing Systems, Phoenix, AZ, USA (2001)Google Scholar
  9. 9.
    Lan, J., Liu, X., Shenoy, P., Ramamritham, K.: Consistency maintenance in peer-to-peer file sharing networks. In: Proc. of WIAPP 2003, 3rd IEEE Workshop on Internet Applications, San Jose, CA, USA, pp. 76–85 (2003)Google Scholar
  10. 10.
    Lan, J.: Cache Consistency Techniques for Peer-to-Peer File Sharing. Technical report, MSc Thesis, Dept. of Computer Science, Univ. of Massachusetts (2002)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Elias Leontiadis
    • 1
  • Vassilios V. Dimakopoulos
    • 2
  • Evaggelia Pitoura
    • 2
  1. 1.Department of Computer ScienceUniversity College LondonUnited Kingdom
  2. 2.Department of Computer ScienceUniversity of IoanninaIoanninaGreece

Personalised recommendations