UsenetDHT : A low-overhead design for Usenet Emil Sit, Robert Morris and Frans Kaashoek (MIT) NSDI 08. Presentation prepared by: Nikos Chondros May 21, 2010 For MDE519. Distributed Systems Prof. Mema Roussopoulos. What is Usenet.
Presentation prepared by: Nikos Chondros
May 21, 2010
For MDE519. Distributed Systems
Figure 1: Messages exchanged during duringUsenetDHT reads and writes. 1. Client A posts an article to his local NNTP front-end. 2. The front-end stores the article in DHash (via a DHash gateway, not shown). 3. After successful writes, the front-end propagates the article's metadata to other front-ends. 4. Client B checks for new news and asks for the article. 5. Client B's front-end retrieves the article from the DHT and returns it to her.
Key owner’s successor
Example for k=2
Figure 5: Durability of objects in Passing Tone: the graph shows a CDF of the number of replicas per object after a one year PlanetLab trace. No objects are lost during this simulation.
Figure 6: Number of crashes within an eight hour window over the course of the PlanetLab trace. Eight hours represents the approximate time needed to replicate the data of one PlanetLab server to another.
UsenetDHT: USA)potential savings