多田研紹介+ アドホックに惑わされる日々

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多田研紹介+ アドホックに惑わされる日々 Powered By Docstoc
					Cache Cooperation
for Clustered Disconnected
Computers

University of Electro-Communications, JAPAN
            YASUDA, Kinuko
          kinuko@spa.is.uec.ac.jp
Introduction
n   Disconnection Problem
    n   Mobile users are often disconnected or
        weakly connected to the server     Server
         n   Intolerable latency
         n   Lack of access to remote resources
n   Possible Solution                               Internet
                                                  (Backbone)
    n   Disconnected Operation
                                  Mobile
                                   User
       Disconnected Operation
       n   Exploits client cache while disconnected


                             disconnect
                 cache                       Server

                                  Cache misses are critical
                                  and may force the users
                                  to stop the current job.
miss   cache
                     cache
       Cache Cooperation
       n   Exploits remote client cache


                             disconnect
                 cache                       Server

                                  Allow clients to retrieve
                                  missing files not only from
                                  the server, but also from
miss   cache                      other clients.
                     cache
    Coda
       Disconnected Hoarding          Logically
(Available Servers = 0)               Reconnected

                    Physically
         Emulating             Resolving
                   Reconnected
                   (Available Servers > 0)


                                                             Server
                                                disconnect
                                                reconnect
                                                    sync
                                        cache
    Cache Cooperation
       Disconnected Hoarding             Logically
(Available Servers = 0)                  Reconnected

         Emulating     Physically
         Emulating                Resolving
        (Cooperating) Reconnected
                      (Available Servers > 0)

  Isolated      Disconnected
  (Available                                                    Server
                (Available                         disconnect
Clients = 0)    Clients > 0)

        Emulating                          cache            cache

         (Isolated)                                             Client
Basic Performance
n   Test Environment
                                                       Server
              3.5MB          (A) Connected
            File Transfer                  4 hops      (S)
     (A)
            10.31sec                   cache
    SàC1                                        (B) Disconnected
     (B)                                         (Remote cache)
              9.67sec
    C1àC2                      cache           cache
     (C)                                             IEEE802.11b
             3.7msec              (C1)          (C2) Wireless LAN
    C1àC1
                            (C) Local cache
Trace Data
Evaluation Result (1)
n   60 min. Hoarding, 60 min. Disconnect
    n   Works great for project-shared files, though
        discouraging result for system files.
Evaluation Result (2)
n   120 min. Hoarding, 60 min. Disconnect
    n   Promising result for system files.

				
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posted:7/28/2013
language:English
pages:10