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IP Storage Tutorial

IP Storage Tutorial. Presented 17 October 2001 by Marc Staimer, President & CDS – Dragon Slayer Consulting Ahmad Zamer, Sr. Product Line Marketing – Intel John Hufferd, Sr. Technical Staff – IBM SSD Joe Gervais, Director Product Marketing – Alacritech. Tutorial Introduction.

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IP Storage Tutorial

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  1. IP Storage Tutorial Presented 17 October 2001 by Marc Staimer, President & CDS – Dragon Slayer Consulting Ahmad Zamer, Sr. Product Line Marketing – Intel John Hufferd, Sr. Technical Staff – IBM SSD Joe Gervais, Director Product Marketing – Alacritech

  2. Tutorial Introduction Marc Staimer, CDS – Dragon Slayer Consulting marcstaimer@earthlink.net

  3. The Purpose of this Tutorial • IP Storage as “block” vs. “file” storage • NAS will be discussed peripherally • To provide details about IP Storage • To provide factual information • To clarify issues • To facilitate understanding • Key point • This is will be pragmatic education not cheerleading

  4. IP Networked Storage iSCSI – New Possibilities Ahmad Zamer Ahmad.zamer@intel.com October 2001

  5. Overview • Introduction • Benefits of IP Storage • IP Storage technologies • iSCSI • Conclusions

  6. Introduction “Ethernet wins. Again. In time… Ethernet will eventually triumph over all other storage networking technologies, including Fibre Channel” Source: March 2001 Forrester Research “If we were starting with a clean piece of paper … we would probably use gigabit Ethernet and IP”Source: Bill Miller CTO StorageNetworks, Industry Standard “... 76% of senior IT executives believe IP will make it easier to implement large-scale storage networks” Source: Enterprise Storage Group 9/11/2000 “75% perceive iSCSI as the IP storage standard” Source: Marc Staimer , Dragon Slayer Consulting – May 2001

  7. Storage Area Network Network Attached Storage Direct Attached Storage • Transmission optimized for file • transactions • Storage traffic travels across the LAN • High Cost of Ownership • In-flexible • Transmission optimized for database • transactions • Separate LAN and SAN • Increases Data availability • Flexible and scalable Network Storage Models

  8. Moving from Dedicated to Networked Storage

  9. Benefits of IP Storage • Brings the SAN concept to Ethernet networks • Lower total cost of ownership • Creates a single integrated network • Makes remote data replication possible • Improves enterprise networks management • Provides higher degree of interoperability

  10. Storage Router iSCSI IP Network GE FC or SCSI Storage appears local to servers Advantages of IP Storage • Storage access over distance • Transparent to Applications • Leverage Benefits of IP • IT Skills • Ethernet & SCSI Infrastructure • Network Management • R&D Investment • Universal Access to Storage

  11. 100Gbps FC Switches IP Storage Switches 40Gbps 10Gbps IP Storage Switches 10Gbps 1Gbps 1.7Gbps FC Switches 0.85Gbps 2000 2001 2002 2003 2000 2001 2002 2003 IP Storage Switches FC Switches IP Storage Switches FC Switches 2000 2001 2002 2003 2000 2001 2002 2003 Key Business Trends Favor IP Storage Network Performance Overall System Cost Trained Staff Available Total Cost of Ownership

  12. Storage Networking Industry Association IP Storage Standards • IETF IP Storage (IPS) Working Group • iSCSI • FCIP • iFCP • iSNS • Storage Networking Industry Association (SNIA) • SNIA IP Storage Forum

  13. IP Storage Technologies

  14. What are the technologies? (iSCSI, iFCP, FCIP) • iSCSI • iSCSI is a TCP/IP-based protocol for establishing and managing connections between IP-based storage devices, hosts and clients • FCIP • FCIP is a TCP/IP-based tunneling protocol for connecting geographically distributed Fibre Channel SANs transparently to both FC and IP • iFCP • iFCP is a TCP/IP-based protocol for interconnecting Fibre Channel storage devices or Fibre Channel SANs using an IP infrastructure in place of Fibre Channel switching and routing elements

  15. IP Storage: iSCSI, FCIP, iFCP End Devices Fabric Services* iSCSI iSCSI/IP InternetProtocol FCIP FibreChannel FibreChannel iFCP FibreChannel InternetProtocol * Fabric Services include routing, device discovery, management, authentication, inter-switch communication

  16. iSCSI, iFCP and FCIP Protocol Stacks Applications Operating System Standard SCSI Command Set New Serial SCSI FCP FC-4 FCP FC-4 FC Lower Layers TCP TCP TCP IP IP IP iSCSI iFCP FCIP

  17. iFCP

  18. Ethernet Header IP TCP iFCP FCP SCSI Data … CRC Checksum iFCP • iFCP is a gateway-to-gateway protocol for implementing a fibre channel fabric over a TCP/IP transport • Traffic between fibre channel devices is routed and switched by TCP/IP network • The iFCP layer maps Fibre Channel frames to a predetermined TCP connection for transport • FC messaging and routing services are terminated at the gateways so the fabrics are not merged to one another • Dynamically creates IP tunnels for FC frames //

  19. iFCP Approach iFCP provides F port to F port connectivity only FC Server FC Tape Library FC Server FC Tape Library Device-to-DeviceSession iFCPGateway iFCPGateway iFCPGateway iFCPGateway IP Network iSNS Server iSNS Server iFCPGateway iFCPGateway iFCPGateway Device-to-DeviceSession iFCPGateway FC Server FC JBOD FC Server FC JBOD IP Services at individual device level IETF Standards for Routing, Naming,Security, QoS, CoS, Discovery (iSNS)

  20. FCIP

  21. FCIP • FCIP encapsulates FC frames within TCP/IP, allowing islands of FC SANs to be interconnected over an IP-based network • TCP/IP is used as the underlying transport to provide congestion control and in-order delivery FC Frames • All classes of FC frames are treated the same as datagrams • End-station addressing, address resolution, message routing, and other elements of the FC network architecture remain unchanged • IP introduced exclusively as a transport protocol for an inter-network bridging function • IP is unaware of the Fibre Channel Payload and the FC fabric is unaware of IP // Ethernet Header IP TCP FCIP FCP SCSI Data … CRC Checksum

  22. FCIP Approach—IP Tunneling FC Server FC TapeLibrary FC TapeLibrary FC Server FC Switch FC Switch FC Switch FC Switch FCIPTunnel FCIPTunnel Fibre Channel SAN Fibre Channel SAN IP Network Tunnel Session FC Switch FC Switch FC Switch IP Services Available at AggregatedFC SAN Level FC Server FCJBOD FC Server FCJBOD FCIP provides E port to E port connectivity

  23. iSCSI

  24. // Ethernet Header IP TCP iSCSI SCSI Data… CRC Checksum iSCSI • iSCSI is a SCSI transport protocol for mapping of block-oriented storage data over TCP/IP networks • The iSCSI protocol enables universal access to storage devices and Storage Area Networks (SANs) over standard TCP/IP networks

  25. // Ethernet Header IP TCP iSCSI SCSI Data… CRC Checksum Ethernet Header // Ethernet Header IP TCP iFCP FCP SCSI Data … CRC IP TCP FCIP FCP SCSI Data … CRC Checksum Checksum iSCSI, iFCP, FCiP

  26. iSCSI – Cont. • iSCSI (Internet SCSI) specifies a way to “encapsulate” SCSI commands in a TCP/IP network connection: IP Header TCP Header iSCSI Header SCSI commands and data Explains how to extract SCSI commands and data Provides information necessary to guarantee delivery Contain “routing” information So that the message can find its Way through the network

  27. iSCSI Deployment

  28. iSCSI Implementations iSCSI Client Native iSCSI Device IP Network iSCSI Gateway FC Switch iSCSI Server Disk

  29. Server and LAN bottlenecks Single points of failure Poor scalability (management overhead, resource inefficiencies) Tape Drives => Tape Library Departmental => Application-centric disc arrays Tape Drive Tape Drive Tape Drive Switch Switch Tape Library NT Servers NT Servers RAID (Email) Mission-Critical RAID (Oracle, ERP DB) LAN Switch Switch SAN RAID RAID RAID Storage Consolidation

  30. iSCSI Architecture • Overview • Architectural Model • Features Beyond // SCSI • Issues Beyond // SCSI

  31. iSCSI - Layered Model • Replaces shared bus with switched fabric • Transparently encapsulates SCSI CDBs • Unlimited target and initiator connectivity

  32. iSCSI Sessions • Session between initiator and target • One or more TCP connections per session • Login phase begins each connection • Deliver SCSI commands in order • Recover from lost connections iSCSI Host iSCSI Device iSCSI Session iSCSI Initiator iSCSI Target TCP Connection TCP Connection iSCSI Target TCP Connection iSCSI Session

  33. TCP CRC I P Ethernet Header DATA SCSI Initiator iSCSI Initiator TCP CRC I P Ethernet Header iSCSI SCSI DATA IP Network CRC FC Header SCSI DATA External Network iSCSI Encapsulation Data Servers End Users iSCSI Target SCSI Target Fibre Channel SAN LUNs

  34. 1 2 3 SCSI Initiator iSCSI Initiator 1 3 2 IP Network 1 2 3 iSCSI Packet Order Data Servers iSCSI Target SCSI Target Fibre Channel SAN LUNs

  35. iSCSI Packet // Ethernet Header IP TCP iSCSI SCSI Data… CRC Checksum

  36. 46–1500 bytes Destination Address Source Address Preamble Type IP TCP Data FCS 8 6 6 2 4 Octet U A P R S F iSCSI Packet Well-known Ports: 21 FTP 23 Telnet 25 SMTP 80 http iSCSI Encapsulated Opcode Opcode Specific Fields 5003 iSCSI Length of Data (after 40Byte header) Destination Port SourcedPort LUN or Opcode-specific fields SequenceNumber Initiator Task Tag AcknowledgmentNumber Opcode Specific Fields Offset Reserved Window Checksum Urgent Pointer Data Field … Options and Padding TCP Header

  37. SCSI Commands Command phase Optional data phase Response phase iSCSI Commands Binds command phase with associated data into iSCSI Protocol Data Unit (PDU) iSCSI Commands

  38. iSCSI Architecture Features Beyond // SCSI • Sessions • Comprises one or more TCP connections used for fail over and/or link aggregation • Device sharing • Any host on the network can potentially use the same iSCSI device • Device scalability • Hosts can connect to an effectively limitless number of iSCSI devices

  39. iSCSI Architecture Issues Beyond // SCSI • Naming, addressing and discovering • Security & Data Integrity • Ordering and numbering • Error handling/recovery • Networking Overhead

  40. iSCSI Architecture IssuesNaming, Addressing & Discovery • // SCSI uses a simple NAD scheme: • Devices discovered by polling the bus • Devices given unique id between 0 and 15 • iSCSI requires: • Internet addressing • Location independent naming • operation beyond firewalls • multiple addresses to one target • multiple targets behind one address • 3rd party commands • Scalable discovery (poll the Internet??)

  41. 1) Host driver requests available iSCSI targets from the SCSI router 2) SCSI router sends available iSCSI target names to host 3) Host logs into iSCSI targets that were received 4) SCSI router accepts the login and sends target identifiers to Host (numbers) 5) Host queries targets for device information 6) Targets respond with device information 7) Host creates table of internal devices (/dev/…) iSCSI Storage Device Discovery Process

  42. Establish normal TCP Session 0X03 Command—Login Send Targets 0X43 Login Response—Reject Login Status 1 In text area, list of assessable target names.Keeps TCP session up. 0X03 Command—Login List of Target names sent 0X43 Login Response Response with target drive mapping iSCSI Sequence Target Initiator Single TCP Session TCP TCP port 5003 This device has already initialized onto the Fibre Channel iSCSI Driver

  43. iSCSI Architecture Issues: Security Levels • 0: None – ok in controlled environments • 1: Initiator and target authentication • Prevents unauthorized access • 2: Digests for header and data integrity • Prevents against man-in-middle, insertion, modification and deletion • 3: Encryption (IPSEC) • Prevents against eavesdropping

  44. iSCSI Architecture Issues Ordering & Numbering • Unlike // SCSI, iSCSI PDUs may • Arrive out of order (by taking different routes) • Not arrive at all • iSCSI requires • Command numbering • Ordered delivery over multiple connections • Status numbering • Detection of a failed connections • Data sequencing • Detection of missing data PDUs

  45. iSCSI Architecture Issues Error Handling & Recovery • // SCSI errors incur costly recovery: • Aborted commands; target, bus and host resets • OK, because bus errors are infrequent • iSCSI errors will be more frequent • Link failures • TCP failures • Bad “middle box” (firewall, router) • Does the Internet have a “reset” option??

  46. iSCSI Architecture Issues Networking Overhead • Software iSCSI can achieve near GbE wire speed – but at 100% CPU • Traditional TCP stacks are expensive • multiple memory copies • too many interrupts • checksums calculations • We needs TCP offload engines (TOE)

  47. Ethernet Header IP TCP iSCSI SCSI Data CRC iSCSI - TCP Offload • Ethernet frame requires additional CPU processing • Headers must be stripped • Packets ordered • Data copied into memory buffers • CRC checked

  48. iSCSI Architecture  Issues  Networking • TOE • The challenge rests on the TOE vendor • Interrupt host on command boundaries • Offer zero-copy from NIC to app • Eliminate TCP reassembly buffer • Provides true zero-copy • Requires RDMA or synchronization • Proposed IETF solutions for framing • WARP - an RDMA mechanism • Markers – a synchronization mechanism

  49. What’s Next for iSCSI • CRC • SLP (Service Location Protocol) • Authentication • Encryption

  50. Conclusions

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