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Storage Wide-Area Networks (SWANs)

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.

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Storage Wide-Area Networks (SWANs)

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  1. 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

  2. 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)

  3. E.g, Hitachi, EMC, IBM Storage Arrays Storage Networks Fibre Channel Loops Dual Ported Disks And Controllers Remote Storage Manager DI DI DI DI Cache Workstation Cache Mainframe Crossbar Interconnect Cache Fibre Channel Or ESCON Cache HI HI HI HI Multiple Host Interconnections

  4. 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

  5. Host Disk Interface (DI) OS Disk, Cylinder,Track, Sector Allocation Table Basic Attached Storage • Device attached by SCSI HBA or channel interface • Host manages the file-to-block mapping

  6. Network-Attached Storage (NAS)aka Network File Service Host • Mapping from File to Block done in network-attached File Server, not host NetworkInterface (NI) Network File Server Host LAN File Name, Offset, Length OS NetworkInterface (NI) Host NetworkInterface (NI)

  7. OS Network-Attached Secure Devices (NASD) Gibson@CMU: Research project on device embedded protocol stack, authentication Host NetworkInterface (NI) Network File Server Host LAN File Name, Offset, Length Disk, Cylinder, Track, Sector OS NetworkInterface (NI) Host NetworkInterface (NI) Network-attached Secure Device (NASD)

  8. OS Storage Platforms“Storage Virtualization” Main Frame LUN = Logical Unit Logical disk mapping onto underlying physical disks on logical block to physical block basis LUN, Offset, Length ChannelInterface Main Frame Disk Storage Subsystem Work Station LUN To PHY

  9. NAS NAS distinguished by an exported Network File System interface over a standard Local Area Network-based transport File Server Host NetworkInterface (NI) Host File Server LAN File Name, Offset, Length NetworkInterface (NI) Host NetworkInterface (NI) File Server

  10. NAS + SAN SAN distinguished by a block-oriented interface;Usually implemented across a channel-oriented fabric Main Frame PHY Device, Cyl, Trk, Sector File Server Disk Storage Subsystem Host NetworkInterface (NI) Channel Interface CI SAN LUN, Offset, Length Host File Server LAN Tape Storage Subsystem LUN, Offset, Length File Name, Offset, Length CI CI NetworkInterface (NI) CI Host Optical Disk Storage Subsystem NetworkInterface (NI) File Server Main Frame

  11. Gate way DSS FS LAN SAN Remote SAN WAN Main Frame Gate way PHY Device, Cyl, Trk, Sector File Server Disk Storage Subsystem Host NetworkInterface (NI) Channel Interface CI SAN LUN, Offset, Length Host File Server LAN Tape Storage Subsystem LUN, Offset, Length File Name, Offset, Length CI CI NetworkInterface (NI) CI Host Optical Disk Storage Subsystem NetworkInterface (NI) File Server Main Frame NAS + SAN + SWAN Now extend the NAS or the SAN over a wide-area network transport … NOTE: wide-area SAN is new idea

  12. Shared StorageReference Model Application File/Record Subsystem Host Service Subsystem Discovery, Monitoring Resource Mgmt, Configuration Security, Billing Redundancy Mgmt, Back-up High Availability, Fail-over Capacity Planning Block Aggregation Storage Domain SAN Device Block Subsystem

  13. SAN Reference Model Block-oriented SAN Application FS File Host-based SAN SAN-based Block Device-based DA

  14. SAN Reference Model Application NAS Storage Host Host LAN FS File NAS Host SAN Block Device

  15. SAN Reference Model Application Heterogeneous Storage Environment Host s/w raid Host Host Host LAN FS File NAS Head NAS Host SAN SAN Block Device DA

  16. Seven Layer Stack 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-4Protocol I/FFC-3 Encrypt/AuthenticationFC-2 Framing, FC,Class of Service FC-1 Encoding,Link Control FC-0 Phy 7 6 5 4 3 2 1 Application Presentation Session Transport Network Data Link Physical

  17. 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

  18. SCSI-3 Terminology Target Initiator Device Server Request LUNs Application Client SCSI Client-Server Model Response Delivery Subsystem (e.g., Fibre Channel orSerial SCSI over IP)

  19. 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? Tape Storage Subsystem Tape Storage Subsystem Server Server WAN IP Network FC Switch FC Over IP FC Over IP FC Switch Server Server JBOD JBOD Tunnel Session

  20. FC Device Address FC_Device N_Port F_Port iFCP layer FCP Portal FC_Device N_Port F_Port iFCP layer FCP Portal FC Traffic IPAddress Mapping Control Data iFCP Frames IP Network iFCP gateway region iFCP gateway region 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

  21. 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

  22. 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

  23. iSNS • Discovery Process • Device registration • WWN or iSCSI names • Zoning/discovery domains • iSNS objects • Portals • Storage Port • Storage Nodes

  24. 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

  25. 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

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