Replica Management
Mansi Radke
mansir1@umbc.edu
Where, when and by whom replicas
should be placed.
Mechanisms to keep them consistent.
Issues:
Replica-server Placement
Content Placement
Replica Server Placement
Distance between clients and locations as
starting point. (latency , bandwidth)
Content Replication and Placement
Client Initiated Replicas
Server Initiated Replicas
Permanent Replicas
Mirroring
Server Initiated Replicas
Initiative of owner of data store
Enhance performance
Client Initiated Replicas
Client caches
Managing is entirely by client
Improve access time
Placement
Same machine
LAN
WAN
Content Distribution
Propagation of Updated content
Propagate only notification of an update
Transfer data from one copy to another
Propagate the update operation to other copies
Invalidation Protocols
Push Vs Pull Protocols
Push
Server based
Read to update ratio is high
High degree of consistency
Multicasting
Pull
Client based
Read to update ratio is low
Unicasting
Lease
References
[1] Micha l Szymaniak, Guillaume Pierre, and Maarten van Steen. Latency-
driven replica placement. In IEEE Symposium on Applications and the
Internet, Trento, Italy, January 2005.
[2] L. Qiu, V. Padmanabhan, and G. Voelker, “On the Placement of
Web Server Replicas,” in Proceedings of IEEE INFOCOM, April
2001, pp. 1587–1596.
[3] P. Radoslavov, R. Govindan, and D. Estrin, “Topology-Informed
Internet Replica Placement,” Computer Communications, vol.
25, no. 4, pp. 384–392, March 2002.
[4] C. Gray and D. Cheriton. Leases: An Efficient Fault-Tolerant
Mechanism for Distributed File Cache Consistency. In Proceedings
of the Twelfth ACM Symposium on Operating Systems Principles,
pages 202–210, 1989.
THANK YOU !