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Modeling and Evaluation of Fibre Channel Storage Area Networks

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Title: Modeling and Evaluation of Fibre Channel Storage Area Networks


1
Modeling and Evaluation of Fibre Channel Storage
Area Networks
  • Xavier Molero, Federico Silla, Vicente Santonia
    and Jose Duato

2
Introduction
  • What is a SAN (Storage Area Network)
  • A separate high-speed network for storage
  • Isolated from messaging network
  • Optimized for moving data between servers and
    storage devices
  • How it is different from traditional
    server-storage network

3
Traditional Server-Storage Architecture
  • Limitations
  • Unavailability of data in case of a failure on
    server
  • Bandwidth saturation during backups

4
Typical SAN Architecture
5
Fibre Channel
  • Generic transport mechanism
  • Provides an interface for high-speed data
    transfer(gigabit per second) and long distance(up
    to 10 km)
  • Standard provides definitions about physical
    layer characteristics, transport control
    protocol, and upper level interface to TCP/IP,
    SCSI, and other protocols
  • Some features are not specified(routing
    algorithm, internal switch architecture)

6
Fibre Channel (cont.)
  • Switching Mechanism
  • virtual cut-through incoming messages are
    forwarded as soon as they are routed and out port
    is free
  • Flow Control Mechanism
  • credit scheme

7
System Model
  • Switch Architecture
  • Network Topology
  • Routing Algorithm
  • Communication Pattern
  • Disk response time model
  • I/O load generation

8
Switch Architecture
9
Switch Architecture
10
Network Topology
  • Single room
  • Regular
  • Fattrees, meshes, multistage networks, and fully
    connected topologies
  • Irregular
  • randomly generated, a single link connects two
    switches
  • Floor topologies

11
Routing Algorithm
  • Distributed routing
  • Leaving routing decisions to each switch
  • Up/down routing (partially adaptive)
  • Based on breadth-first spanning tree(BFS)
  • Minimal adaptive routing (fully adaptive)

12
Communication Pattern
  • Request parameters
  • Disk ID
  • Access type (read or write)
  • Starting location (sector number)
  • Requested size

13
Communication Pattern
14
Disk Response Time Model
  • A single server queue with a FIFO discipline
    service
  • Composed of three parts
  • Seek time
  • Rotational latency
  • Transfer time

15
Disk Response Time Model
16
I/O Load Generation
  • Use auto-similar arrival pattern
  • Real traffic is bursty and the bursts exist over
    many time scales
  • Model each server as a set of ON/OFF sources
  • Model the length of ON/OFF periods with Pareto
    distribution
  • Simulator can be feed with real-world I/O traces

17
Evaluating SANs Performance
  • Effect of switch architectures on performance
  • Effect of faulty links on performance

18
Effect of Switch architecture
19
Effect of Switch architecture
20
Effect of Failures in Links
21
Effect of Failures in Links
22
Summary
  • SAN is a alternative to traditional
    server-to-disk approach
  • Fibre channel is a prominent technology for
    implementing SAN.
  • The simulator considers a wide set of
    characteristics and is a key tool for the design
    and evaluation of SANs.

23
Questions
  • What is a storage area network?
  • What are the limitations of traditional
    server-storage architecture?
  • Name some features of fiber channels.
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