DaveWentzel.com            All Things Data

FibreChannel

 

Fibre Channel

  • Dominates the SAN market since the mid 1990's.  Most SANs are FC. 
  •  

  • FC can be both the linking technology between physical disks, as well as the connecting technology in a "switched fabric" or a fiber loop. 
  •  

     

    Topology
    Name
    Notes
    Arbitrated Loop
    FC-AL
    • ring or loop
    • 126 devices (NL_Ports)
    • one additional port for attachment to a fabric (FL_Port)
    Point to Point
    Direct Connect
    used in smaller environments where there are few servers and/or many ports on the storage device. 
    Switched
    Fabric
    Switches are interconnected with expansion ports (E_Port).  Maximum 239 switching devices in a fabric.  This is a domain.  You can then connect fabrics either physically or logically. 
     
     
     

     

     
  • Takes away many of the limitations of SCSI...cable lengths, more connected servers, more physical disks, etc. 
  •  

  • uses the SCSI command language
  •  

  • 24 bit addresses (2^24 ports basically) in switched fabric. 
  •  

  • Has dual ports on the disk for high availability (like SAS).
  •  

  • FC can work over an IP network as well using
    • FCIP or
    • iFCP protocols
  •  

  • Protocol Layers
    • FC-1: handles 8/10 bit encoding. 
    • FC-2: handles flow control and Classes of Service. 
  •  

     

    OSI Layer
    Name
    FibreChannel Equivalent
    7
    Application
     

    FileSystem, IP, FICON, etc. 

    6
    Presentation
     
    5
    Session
     
    4
    Transport
     
    3
    Network
     
    2
    Data Link
    FC-3:  services
    FC-2:  flow control and Classes of Service
    1
    Physical
    FC-1:  8/10 bit encoding
    FC-0
     
     
     

     

  • The max potential bandwidth of a FC connection in a 4GB SAN is 800 MBps. 
  •  

  • A Fibre Channel bridge enables a FC host to connect to a legacy parallel SCSI storage device. 
  •  

  •  

     

     

     

    SAN Home

    Add new comment