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Introduction to Storage Area Networks – I iSCSI & FCIP Ashish Shah Cisco Systems, Inc. [email protected] BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 1 Agenda iSCSI – – – – – What is iSCSI Login and Session Establishment Basic IO Advanced Concepts Initiators and Targets FCIP – What is FCIP – FCIP Case Study References BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 2 iSCSI BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 3 What is iSCSI RFC3720 - Internet Small Computer Systems Interface A SCSI transport protocol that operates on top of TCP – Encapsulates SCSI CDBs (Command Descriptor Blocks) and data into TCP/IP byte-streams – Allows IP hosts to access IP based SCSI targets Broad industry support – Server vendors now publishing own supported iSCSI drivers – Native iSCSI storage arrays now appearing IP BITS Pilani Alumni Association (www.bitsaa.org) TCP iSCSI SCSI Introduction to SAN – 1: iSCSI & FCIP Data November 19, 2006 4 iSCSI Architectural Model SCSI Applications (File Systems, Databases) SCSI Device-Type Commands SCSI Generic Commands SCSI Transport Protocols SCSI Block Commands SCSI Stream Commands SCSI Commands, Data and Status Parallel SCSI Transport FCP SCSI over FC iSCSI SCSI over TCP/IP TCP Layer 3 Network Transport Layer 2 Network Other SCSI Commands IP Parallel SCSI Interfaces BITS Pilani Alumni Association (www.bitsaa.org) Fibre Channel Introduction to SAN – 1: iSCSI & FCIP Ethernet, PPP, HDLC… November 19, 2006 5 iSCSI Conceptual model iSCSI Initiator Entity Network Entity – An object that can have multiple iSCSI nodes iSCSI node: Iqn.com.cisco.init-1 iSCSI Node Network Portal (10.1.1.2) – Initiator or Target node – Identified by an iSCSI Name – iSCSI Target node can have multiple LUs IP Network Network Portal Network Portal (IP 20.1.1.5) iSCSI node: Iqn.com.cisco.disk-1 Network Portal (IP 20.1.1.20) iSCSI node: Iqn.com.cisco.disk-2 – Provides a mechanism to access the iSCSI nodes – Identified by a Network address (IP) iSCSI Target Entity BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 6 iSCSI Sessions iSCSI has the concept of a session between an initiator and a target – Loosely equivalent to a SCSI I-T Nexus – It can have one or more TCP connections – Session establishment has three phases • Security authentication, Operational negotiation and Full Feature Discovery Sessions – Discover the targets in the network entity – Initiator executes “SendTargets” command after establishing the session • This is the only command supported for a Discovery session Target Sessions – Sessions to specific targets – Supports normal SCSI commands BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 7 Discovery Session Login Initiator TCP iSCSI Initiator Login (Discovery Session) Target Establish TCP Session TCP port 3260 Command - Login Session type: Discovery-Session iSCSI Driver Optional Authentication Phase Command - SendTargets Response Target list: com.cisco.Target-disk1 Com.cisco.Target-Disk2 BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 8 Target Session Login Target Initiator TCP Establish TCP Session TCP port 3260 Command - Login Session-Type: Normal-Session, Target: com.cisco.Target-disk1 iSCSI Driver Optional Authentication Phase Operational Parameter Negotiation After this completes we are in full feature mode Command – SCSI commands Normal SCSI commands… BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 9 Common iSCSI Identifiers PGT: Portal Group Tag – Tag identifying a set of Network Portals that can support sessions with multiple connections spanned across these portals ISID: Initiator Session Identifier – Specified by the initiator during login SSID: Session Identifier – Composed of the {ISID, Target PGT} TSIH: Target Session Identifying Handle – A Target assigned tag to identify sessions on its end ITT: Initiator Task Tag – Identifies an iSCSI Task BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 10 iSCSI Naming iSCSI name can be either : – IQN (iSCSI Qualified Name) • iqn => iqn.yyyy-mm.reverse-FQDN-[:|.]-and-qualifier-string • For example, iqn.1921-02.com.cisco.cluster1.mbr2 – EUI-64 name (Extended Unique Identifier) • eui.EUI-64 • For example, eui.02004567A425678D BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 11 iSCSI Packet Format 46–1500 Bytes Destination Source Address Address Preamble 8 6 Well-Known Ports: 21 FTP 25 SMTP 80 HTTP 3225 FCIP 3260 iSCSI Type 6 IP TCP Data FCS 2 iSCSI Targets Will Listen on This Port (by Default) 4 Octet Opcode Opcode-Specific Fields Length of Data (After 40-Byte Header) Offset Offset Source Source Port Port Destination Port Sequence Number Sequence Number Acknowledgement Number Acknowledgment Number Reserved U A P R S F Window Reserved U A P R S F Checksum Urgent Pointer Checksum Options and Padding Initiator-Task Tag Opcode-Specific Fields Data Field… SCSI Encapsulated TCP Header BITS Pilani Alumni Association (www.bitsaa.org) LUN or Opcode-Specific Fields Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 12 iSCSI Read Sequence Initiator Target SCSI Command : ITT: 100, CmdSN: 110, ExpStatSN 50 SCSI Data-In: ITT 100, ExpCmdSN: 111, MaxCmdSN: 115, DataSN: 1 SCSI Response: ITT 100, ExpCmdSN: 111, MaxCmdSN: 116, ExpDataSn: 3, StatSN: 50 BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 13 iSCSI Write Sequence Initiator SCSI Command : ITT: 100, CmdSN: 110, ExpStatSN 50 Target R2T : ITT: 100, TTT: 10 R2TSN: 10 SCSI Data-Out: ITT 100, : 111, TTT: 10, DataSN: 1, ExpStatSN: 1 SCSI Response: ITT 100, ExpCmdSN: 111, MaxCmdSN: 116, StatSN: 50 BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 14 More iSCSI Concepts Error Recovery Levels (ERL 0/1/2) – Progressively higher level of error recovery capability • 0 => Session failure recovery • 1 => Digest failure recovery • 2 => Connection recovery iSCSI Header and Data Digests – Integrity protection only – Use of IPSec recommended for security Task Management Functions – Derived from SCSI TMFs BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 15 iSCSI Initiators Applications File System iSCSI Software Driver Block Device Applications File System iSCSI Software Driver and Dedicated Hardware Block Device SCSI Generic SCSI Generic iSCSI iSCSI TCP/IP Stack TCP/IP Stack NIC Driver Adapter Driver NIC Adapter SCSI Adapter NIC Driver Adapter Driver TOE Adapter SCSI Adapter iSCSI Windows & Linux iSCSI initiators freely available BITS Pilani Alumni Association (www.bitsaa.org) iSCSI HBA: both iSCSI & TCP offloaded to hardware TOE: Only TCP Offloaded Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 16 iSCSI Targets Native iSCSI Targets just appearing in the market iSCSI Gateway products have been on the market for a longer time – Exports backend FC targets through virtual iSCSI targets – Allows iSCSI initiators to access FC targets – Allows customers to introduce iSCSI initiators to existing FC SANs BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 17 iSCSI Gateway on Cisco MDS Real iSCSI Initiator IP Addr 10.1.1.1 iqn.initiator.abc iSCSI IP Network Virtual iSCSI Target IP Addr 10.1.1.2 iqn.target.abc iSCSI Virtual FC Initiator pWWN 12:34…56 fcid 0x550001 FC Fibre Channel Fabric FC FC Targets Presented as iSCSI Targets iqn.def.123 iqn.ghi.456 Real FC Target pWWN 12:34…78 fcid 0x550002 iSCSI Initiators Presented as FC Initiators pWWN d pWWN a iSCSI FC IP iSCSI iqn.abc.123 iqn.jkl.555 iSCSI Storage View BITS Pilani Alumni Association (www.bitsaa.org) pWWN c pWWN b Fibre Channel SAN View Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 18 FCIP BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 19 What is FCIP RFC 3821 – Fibre Channel over TCP/IP Method to encapsulate FC traffic and send over an IP network – Encapsulating TCP connections are called FCIP Tunnels Connects physically separate SANs through E/TE ports over an IP network – Forms a unified SAN in a single Fibre Channel fabric. – FC Fabric and all FC devices are unaware of the presence of the IP Network Motivation is to connect physically remote FC sites to allow remote disk access, tape backup and live mirroring BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 20 FCIP… Advanced features help throughput: – Write Acceleration • Spoofing Transfer Ready locally – Tape Acceleration • Spoofing Tape commands locally – Compression BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 21 FCIP Case Study BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 22 Cisco IT SAN Case Study BEFORE FCIP: Host-Based Replication Source: Cisco IT@Work Case Study: FCIP and EMC SRDF/A. November 14, 2005 © 2005 Cisco Systems, Inc. All rights reserved. BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 23 Cisco IT SAN Case Study… AFTER FCIP: Array-Based Replication Source: Cisco IT@Work Case Study: FCIP and EMC SRDF/A. November 14, 2005 © 2005 Cisco Systems, Inc. All rights reserved. BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 24 iSCSI & FCIP References IETF IP Storage (IPS) Chapter http://www.ietf.org/html.charters/ips-charter.html – List of all relevant RFCs, mailing lists and working group details Storage Networking Industry Association (SNIA) – www.snia.org BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 25 Q&A BITS Pilani Alumni Association (www.bitsaa.org) Introduction to SAN – 1: iSCSI & FCIP November 19, 2006 26