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sahara.cs.berkeley.edu sahara.cs.berkeley.edu Presentation Transcript

  • Storage Wide-Area Networks (SWANs) Randy H. Katz Computer Science Division Electrical Engineering and Computer Science Department University of California, Berkeley Berkeley, CA 94720-1776
  • Storage Networks
    • Primary goal is to share storage among computers in complex, heterogeneous environments, with PCs, workstations, file servers, and mainframes
    • Storage can be:
      • Direct attached (e.g., host bus adapter/HBA)
      • Network attached (via a file server)
      • Channel attached (primarily fibre channel, but also IBM SSA)
  • Storage Networks Workstation HI Cache Fibre Channel Loops Dual Ported Disks And Controllers HI HI HI DI DI DI DI Cache Cache Cache Crossbar Interconnect Mainframe Remote Storage Manager Fibre Channel Or ESCON Multiple Host Interconnections E.g, Hitachi, EMC, IBM Storage Arrays
  • Storage Networks
    • Major development in 1990s: storage networks
      • Native FC is a point-to-point or loop/string-oriented (“arbitrated”) method of interconnection; 1 Gbps, extend up to 10 km
      • Emergence of FC “fabrics”: FC switches arranged hierarchically to enable connectivity between any host and any storage device (e.g., Brocade Networks dominates this product space)
      • Standardize FC protocol stack lives on top of such fabrics: device naming, transport, CoS, etc.
      • SCSI-3 protocol over FC fabrics
      • Gigabit ethernet now emerging in SAN environment
  • Basic Attached Storage
    • Device attached by SCSI HBA or channel interface
    • Host manages the file-to-block mapping
    Host OS Disk Interface (DI) Allocation Table Disk, Cylinder,Track, Sector
  • Network-Attached Storage (NAS) aka Network File Service
    • Mapping from File to Block done in network-attached File Server, not host
    LAN Host Host Host Network File Server OS Network Interface (NI) Network Interface (NI) Network Interface (NI) File Name, Offset, Length
  • Network-Attached Secure Devices (NASD) LAN Host Host Host Network File Server OS Network Interface (NI) Network Interface (NI) Network Interface (NI) Network-attached Secure Device (NASD) File Name, Offset, Length Disk, Cylinder, Track, Sector [email_address] : Research project on device embedded protocol stack, authentication OS
  • Storage Platforms “Storage Virtualization” Disk Storage Subsystem Work Station Main Frame Main Frame Channel Interface LUN, Offset, Length LUN To PHY LUN = Logical Unit Logical disk mapping onto underlying physical disks on logical block to physical block basis OS
  • NAS LAN Host Host Host Network Interface (NI) Network Interface (NI) Network Interface (NI) File Name, Offset, Length File Server File Server File Server NAS distinguished by an exported Network File System interface over a standard Local Area Network-based transport
  • NAS + SAN Optical Disk Storage Subsystem SAN Main Frame Disk Storage Subsystem Tape Storage Subsystem Channel Interface LAN Host Host Host Network Interface (NI) Network Interface (NI) Network Interface (NI) File Name, Offset, Length File Server File Server File Server CI LUN, Offset, Length Main Frame CI CI CI LUN, Offset, Length PHY Device, Cyl, Trk, Sector SAN distinguished by a block-oriented interface; Usually implemented across a channel-oriented fabric
  • NAS + SAN + SWAN Now extend the NAS or the SAN over a wide-area network transport … NOTE: wide-area SAN is new idea Optical Disk Storage Subsystem SAN Main Frame Disk Storage Subsystem Tape Storage Subsystem Channel Interface LAN Host Host Host Network Interface (NI) Network Interface (NI) Network Interface (NI) File Name, Offset, Length File Server File Server File Server CI LUN, Offset, Length Gate way WAN Gate way LAN SAN Main Frame FS DSS Remote SAN CI CI CI LUN, Offset, Length PHY Device, Cyl, Trk, Sector
  • Shared Storage Reference Model Application Host SAN Device File/Record Subsystem Block Subsystem Storage Domain Service Subsystem Discovery, Monitoring Resource Mgmt, Configuration Security, Billing Redundancy Mgmt, Back-up High Availability, Fail-over Capacity Planning Block Aggregation
  • SAN Reference Model Application Block File FS Host-based SAN-based Device-based DA SAN Block-oriented SAN
  • SAN Reference Model Block File FS Host SAN Device LAN NAS Host Host NAS Storage Application
  • SAN Reference Model Block File FS Host SAN Device LAN NAS Host Host Heterogeneous Storage Environment Application NAS Head SAN DA Host Host s/w raid
  • Seven Layer Stack 7 6 5 4 3 2 1 Application Presentation Session Transport Network Data Link Physical IP NFS, CIFS FTP, SNMP, TFTP, Telnet, FCP, SCSI-3 TCP, UDP IP LAN, MAN, WAN Phy Sw GigaE NFS, CIFS FTP, SNMP, TFTP, Telnet, FCP, SCSI-3 TCP, UDP IP Mac Client/ Control Phy FC SCSI-3 VI IP FC-4 Protocol I/F FC-3 Encrypt/ Authentication FC-2 Framing, FC, Class of Service FC-1 Encoding, Link Control FC-0 Phy
  • Fibre Channel Protocol Stack
    • FC-0: gigabit physical layer
    • FC-1: data encoding and link layer control
    • FC-2: segmentation/reassembly of data frames, flow control, class of service
    • FC-3: common services, e.g., encryption
    • FC-4: “upper layer protocol” upon which SCSI-3 or IP can run
    • Contrast with Gigabit Ethernet
      • Ethernet framing, VLAN tagging, frame prioritization (8 levels), link aggregation, 1.25 gbps
      • IP + Gigabit Ethernet emerging for SANs
  • SCSI-3 Terminology Application Client Device Server Request Response Initiator Target LUNs Delivery Subsystem (e.g., Fibre Channel or Serial SCSI over IP) SCSI Client-Server Model
  • FC over IP (FCIP)
    • IETF IP Storage (IPS) working group
      • Recall FC fabrics developed in context of machine room/building-scale interconnect (e.g., no congestion control!)
        • FC time outs in wide-area? Flow control interaction? QoS?
        • How does bridging actually work for FC e2e management?
    WAN Server JBOD Server Tape Storage Subsystem FC Over IP FC Switch Server JBOD Server Tape Storage Subsystem FC Switch FC Over IP Tunnel Session IP Network
  • Internet FC Protocol (iFCP)
    • Gateway to gateway protocol, sessions rather than tunnels
    • TCP for congestion control, error detection, recovery
    • Plug FC devices directly into iFCP switches
    • Session and naming semantics
    FC_Device N_Port F_Port iFCP layer FCP Portal FC_Device N_Port F_Port iFCP layer FCP Portal FC Traffic IP Network FC Device Address IP Address Mapping Control Data iFCP gateway region iFCP gateway region iFCP Frames
  • iFCP Services
    • 24-bit N-Port Address: <Domain, Area, Port>
    • iSNS: Internet Storage Name Service—discovery and management protocol for IP storage networks (IPNSP)
    • Protocol specification includes address translation feature to allow remote storage devices to be assigned a local, FC fabric compliant address
      • Local commands executed locally on the fabric
      • Remote commands executed on top of TCP connections
    • Error Detection/Time Outs
    • Security
  • Other Protocols
    • Metro Fibre Channel Protocol (mFCP)
      • FCP over IP using UDP rather than TCP (link layer flow control and pacing)
    • Internet SCSI (iSCSI)
      • IP to the storage device
      • Serial SCSI block data transfer over IP (SCSI Access Method Command Set—SAM)
      • IPSec, command/data ordering, steering to application memory
  • iSNS
    • Discovery Process
      • Device registration
      • WWN or iSCSI names
      • Zoning/discovery domains
    • iSNS objects
      • Portals
      • Storage Port
      • Storage Nodes
  • Storage Applications
    • Data Centers
      • Server clustering
      • Storage centralization, consolidation, management
      • LAN-free back-up
    • IP Storage for Remote Applications
      • Remote back-up
      • Remote mirroring
      • Disaster recovery
      • Content distribution
  • Rhapsody Networks, Inc.
    • Storage Application Director
      • “ Alteon box for storage networks”
      • Peek into storage packets traversing fabric (“deep frame classification”) and invoke code—for encryption/decryption, mirroring, LUN mappings, etc.
      • Per port software processing and cut-through fabric routing
      • Data copy engine, table lookup engine, in-transit I/O mods, data escrow/trap to software for complex errors or event processing
      • Intelligent queue management