SNS review

From: Praveen Rao (psrao_at_windows.microsoft.com)
Date: Sun Mar 07 2004 - 12:31:14 PST

  • Next message: Manish Mittal: "Cluster-based Scalable Network Services"

    advantages of cluster discussed - scalability, high availability, cost
    effectiveness
    disadvantages of clusters - administration, component vs. system
    replication, partial failures, shared state

    Partial failures and shared state lead to focus on sharing semantics

    ACID: high cost and complexity, but ACID does not guarantee availability
    BASE: (Basically available, soft state, eventual consistency)
    * tolerating stale data for a while
    * soft state
    * approximate answers

    BASE trades off consistency for availability.

    Authors focus on services that have an ACID component but manipulate
    primarily BASE data.

    SNS (scalable network service) features:

    Front end
    Worker pool
    Customization database
    Manager
    Graphical monitor
    SAN

    Design goal: Separating service from implementation.

    Three layers:
    SNS
    TACC
    Service

    *Worker stub hides fault tolerance, provides load balancing and
    multi-threading
    *Manager stub provides dispatch logic

    Features:

    *Centralized load balancer
    *Queue length as a metric for load balancing

  • Next message: Manish Mittal: "Cluster-based Scalable Network Services"

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