`
`OAL.~
`HOUSTON
`MOSCOW
`Nl:W YORK
`"'ASHINOTO>c, D.c.
`
`\.
`
`BAKER & BOTTS
`L..L.1!
`
`1$00 SAN ..IACIHTO CCNTER
`98 SAlf JAONTO Gt.VO.
`AUSTIN, 't£XAS 78701-4039
`
`TCLCPHONC: 15117 322-ZSOO
`rACSIMl~O 1&1a »Z-ZSOI
`
`July 11. 1997
`
`Mr. Geoffrey Hoese
`CrossRoads Systems. Inc.
`9390 Research
`Suite2-300
`Austin Texas 78759
`
`dhod /or ProvJl/ing
`Re: U.S. Patent Application Entitled Storage Router and Mi
`Virtual Local Storage
`Our File No. 064113.0103
`
`Dear Geoff:
`
`t. Please review the I enclose a copy of tbe above-identified applicadon for paten
`.
`
`application to determine if it accurately and adequately describes your inv
`ention, including the
`
`best mode of practicing the invcnlion. After you have completed your review , please contact me
`I will i.ocorporate your comments and place
`lhe application in
`regarding your comments.
`condition for filing and will then send the original to you for f onnal cxecut
`ion.
`
`Should you have any questions cooceming Ibis matter, please
`do not hesitate to call
`me at (512) 322-2599.
`·
`
`Si.ocerely yours,
`
`Anthony E. Peterman
`
`.
`
`AEP/rinf
`Enclosures
`
`AUSOl :llOl19.I
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`Confidential I
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`,'f~• EXHIBIT'4:!:,
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`f1·00-r..A.-~1-r.JJ
` CROSSROADS EXHIBIT 2303
`Oracle Corp., et al v. Crossroads Systems, Inc.
` IPR2014-01207 and IPR2014-1209
`
`CROSSROADS EXHIBIT
`Oracle Corp. v. Crossroads Systems, Inc.
`IPR2015-0(cid:1005)(cid:1004)(cid:1010)(cid:1010)
`
`2303
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`PATD'l' APPLICATIOfi
`
`STORAGE ROUTER AND METHOD FOR
`PROVIDING VIRTOAL LOCAL STORAGE
`
`TECHNICAL PIBT.p OF THE IWSNTIOH
`This invention relates in general to network storage
`devices, and more particularly to a storage router and
`method for providing virtual local storage on remote SCSI
`storage devices to Fibre Channel devices.
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`BA<:lt:GROmm OF THE INYENTION
`Typical storage transport mediums provide for a
`relatively small number of devices to be attached over
`relatively short distances. One such transport medium is
`a Small computer System Interface (SCSI·) bus, the
`structure and operation of which is generally well known.
`High speed serial interconnects provide enhanced
`capability to Attach a large number of high speed devices
`to a conunon storage transport medium over large
`distances. One such serial interconnect is a Fibre
`Channel, the structure and operation of which is
`described, for example, in Fibre Channel Physical a.nd
`
`Signaling Interface (FC-PH}, ANSI X3T9.3/Project ?SSD;
`
`Fibre Channel Arbitrated Loop (FC-AL), ANSI X3T11/Project
`
`15
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`9600; Fibre Channel Private Loop Direct Attach (FC-PLDA)
`
`Technical Report, Fibre Channel System Initiative;
`
`GigaBaud Link Module (GLM) Family, Fibre Channel System
`Initiative, FCSI-301; Common FC-PH Feature Sets Profiles,
`Pibl:'e ·~amut,l .. System Initiative, FCSI-101; SCSI Pro:file,
`.. "'::
`.
`F~~nft!~ System Initiative, FCSI-201; and FCSI IP
`· ~··-=?Jh
`.Proftl•,· •ibre Channel System Initiative, FCSI-202.
`Conventional computing devices, such as computer
`workstations, generally access storage locally or through
`network interconnects.
`t.ocal storage typically consists
`of a disk drive contained within, or locally connected
`to, the workstation. Access to the local storage device
`is through native low level, block protocols that map
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`directly to the mechanisms used by the storage device and
`consist of data reque•ts with no specific structure and
`no security controls. Network interconnects typically
`provide access for a large number of computing devices to
`data storage on a remote network server. The remote
`network server provides file system structure, access
`control, and other miscellaneous capabilities. Access to
`the data through the network •erver is through protocols
`that map to the file system constructs implemented by the
`server and involve high level protocols. Consequently,
`from the perspective of a workstation, or other computing
`device, seeking to access such data, the access is much
`slower than access to data on local storage .
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`SIJMMARY OF THE INYENTION
`In accordance with the present invention, a storage
`router and method for providing virtual local storage on
`remote SCSI storage devices to Fibre Channel devices are
`disclosed that provide advantages over conventional
`network storage devices and methods.
`According to one aspect of the present invention, a
`storage router and storage network provide virtual local
`storage on remote SCSI storage devices to Fibre Channel
`devices. A plurality of Fibre Channel devices, such as
`workstations, are connected to a Fibre Channel transport
`medium, and a plurality of SCSI storage devices are
`connected to a SCSI bus transport medium. The storage
`router interfaces between the Fibre Channel transport
`medium and the SCSI bus transport medium. The storage
`router maps between the workstations and the SCSI storage
`devices and implements access controls for storage space
`on the SCSI storage devices. The storage router then
`allows acce9• from the workstations to the SCSI storage
`device• Ulling native low level, block protocol in
`ac~e with the mapping and the access controls.
`According to another aspect of the present
`invention, virtual local storage on remote SCSI sto~age
`devices is provided to Fibre Channel devices. A Fibre
`Channel transport medium and a SCSI bus transport medium
`are interfaced with. A configuration is maintained for
`SCSI storage devices connected to the SCSI bus transport
`medium. The configuration maps between Pibre Channel
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`devices and the SCSI •torage devices and implements
`access controls for storage space on the SCSI storage
`devices. Access is then allowed from Fibre Channel
`initiator devices to SCSI storage devices using native
`low level, block protocol in accordance with the
`configuration.
`A technical advantage of the present invention is
`the ability to centralize local •torage for networked
`workstations without any cost of speed or overhead.
`sach
`workstation access its virtual local storage as if it
`work locally connected. Further, the centralized storage
`devices can be located in a significantly relIIOte position
`up to ten kilometers using Fibre Channel.
`Another technical advantage of the present invention
`is the ability to centrally control and administer
`storage space for connected users without limiting the
`speed with which the users can access local data.
`In
`addition, global access to data, backups, virus scanning
`and redw:idancy can be 1110re easily accomplished by
`-·.. .. ~ ·:
`.
`~·: leeated storage d.evices.
`llff.:~~ technical advantage of the present
`i~tion is providing support for SCSI storage devices
`as local atorage for Fibre Channel hosts.
`In addition,
`the present invention helps to provide extended
`capabilities for Fibre Channel and for management of
`storage subsystems.
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`BRIRF PBSCR.IfTION OF TBS DJW(INQS
`A more complete understanding of the pre1Jent
`invention and the advantages thereof may be acquired by
`referring to the foll01ting description taken in
`conjunction with the accompanying drawings, in which like
`reference numbers indicate like features, and wherein:
`FIGURE l is a block diagram of a conventional
`network that provide& storage through a network server;
`FIGCRE 2 ie a block diagram of one embodiment of a
`storage network with a storage router that provides
`global access and routing;
`FIGURE 3 is a block diagram of one embodiment of a
`storage network with a storage router that provides
`virtual local storage;
`FIGURE 4 is a block diagram of. one embodiment of the
`storage router of FIGURE 3; and
`FIGURE 5 is a block diagram of one embodiment of
`data flew within the storage router of FIGURE 4.
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`DETAII.Bp DBSCB,IPTIQN OF THE UMWTION
`PIGORE 1 ia a block diagram of a conventional
`network, indicated generally at 10, that provides access
`to storage through a network server.
`1>.J3 shown, network
`10 includes a plurality of workstations 12 interconnected
`with a network server 14 via a network transport medium
`16. Each workstation l~ can generally comprise a
`processor, memory, input/output device•, •torage devices
`and a network adapter as well as other common computer
`components. Network server 14 uses a SCSI bus 18 as a
`storage transport medium to interconnect with a plurality
`of storage devices 20 (tape drives, disk drives, etc.).
`In the embodiment of FIGURE 1, network transport medium
`16 is an ETHERNET connection and storage devices 20
`comprise hard disk drives, although there are numerous
`alternate network transport mediums and storage devices.
`In network 10, each workstation 12 has access to its
`local storage device as well as network access to data on
`atair,&ge dav~~s 20. The access to a local storage device
`~ · ~cally through native low level, block pro~ocols.
`a.·~~ ·)aand, access by a workstation 12 to storage
`•
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`devices ~o requires the participation of network server
`14 which implements a file system and transfers data to
`workstations 12 only through high level file system
`protocols. Only network server 14 communicates with
`storage devices 20 via native low level, block protocols.
`Consequently, the network access by workstations 12
`through network server 14 is slow with respect to their
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`access to local storage.
`Because of the slow access to data on storage
`devices 20, it is not feasible for work9tations 12 to use
`storage devices 20 for work space. Typically,
`application software and data, maintained on the network
`storage devices 20, will be downloaded to local storage
`at workstations 12 for execution and active use.
`In
`addition, other files are often created at or loaded onto
`workstations 12 by the various users. As a result, it is
`a logistical problem to manage and administer localized
`data across an organization. Administrative tasks such
`as backups, virus scanning and redundancy are difficult
`or impossible to accomplish with respect to local
`storage.
`FIGURE 2 is a block diagram of one embodiment of a
`storage network, indicated generally at 30, with a
`storage router that provides global access and routing.
`This environment is significantly different from that of
`In
`PIQQRS l~'iza that there is no network server involved.
`1' . . ·2" .. a ~bre Channel high speed serial transport 32
`i~•· a plurality of workstations 3G and storage
`.;
`devices 38. A SCSI bus storage transport medium
`interconnects workstations 40 and storage devices 42. A
`storage router 44 then serves to interconnect these
`mediums and provide devices on either medium global,
`transparent access to devices on the other medium.
`Storage router 44 routes requests from initiator devices
`on one medium to target devices on the other medium and
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`routes data from the target to the initiator. Storage
`router 44 can allow initiators and targets to be oo
`either side.
`In this manner, storage router 44 enhances
`the functionality of Fibre Channel 32 by providing
`access, for example, to legacy SCSI storage devices oo
`SCSI bus 34.
`In the embodiment of FIGURE 2, the
`operation of storage router 44 can be managed by a
`managell!ent station 46 connected to the storage router via
`a direct serial connection.
`In storage network 30, any workstation 36 or
`workstation 40 can access any storage device 38 or
`storage device 42 through native low level, block
`protocols, and vice versa. This functionality is enabled
`by storage router 44 which routes requests and data as a
`generic transport between Fibre Channel 32 and SCSI bus
`34. Storage router 44 uses tables to map devices from
`one medium to the other and distributes requests and data
`across Fibre Channel 32 and SCSI bus 34 without any
`security~~,. controls. Although this extension of the
`hif'1 .p..d~.9rial interconnect provided by Fibre Channel
`i; t'
`3:t.~:itnrwfi~al, it is desirable to provide security
`controls in addition to extended access to storage
`devices through a native low level, block protocol.
`FIGORE 3 is a block diagram of one embodiment of a
`storage network, indicated generally at so, with a
`storage router that provides virtual local storage.
`Similar to that of FIGURE 2, storage network SO includes
`a Fibre Channel high speed serial interconnect 52 and a
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`SCSI bus 54 bridged by a storage router 56. Storage
`router 56 of PIGORB 3 provide• for a large number of
`workstations 58 to be interconnected on a common storage
`transport and to access common storage devices 60, 62 and
`64 through native low level, block protocols.
`According to the present invention, storage router
`56 has enhanced functionality to implement security
`controls and routing such that each workstation 58 can
`have access to a specific subset of the overall data
`stored in storage devices 60, 62 and 64. This specific
`subset of data has the appearance and characteristics of
`local storage and is referred to herein as virtual local
`storage. Storage router 56 allows the configuration and
`modification of the storage allocated to each attached
`workstation 58 through the use of mapping tables or other
`mapping techniques.
`As shown in FIGURE 3, for example, storage device 60
`can be configured to provide global data 65 which can be
`acc-.aeid by.all workstations SB. Storage device 62 can
`..
`be . Cla:ti~ to provide partitioned subsets 66, 68, 70
`""".'.·' ., '
`&D4~'7f~ · •ra each partition is allocated to one of the
`workstations 58 (workstations A, B, c and D). These
`subsets 66, 68, 70 and 72 can only be accessed by the
`associated workstation 58 and appear to the associated
`workstation 58 as local storage accessed using native low
`level, block protocols. Similarly, storage device 64 can
`be allocated as storage for the remaining ~orkstation Sa
`(workstation E) .
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`Storage router 56 combines access control with
`routing such that each workstation 58 has controlled
`access to only the specified partition of storage device
`62 which forms virtual local storage for the workstation
`58. Storage router 56 allows this allocation of storage
`devices 60, 62 and 64 to be managed by a management
`station 76. Management station 76 can connect directly
`to storage router 56 via a aerial connection or,
`alternately, can interface with storage router 56 through
`either Fibre Channel 52 or SCSI bus 54.
`In the latter
`case, management station 76 can be a workstation or other
`computing device with special rights such that storage
`router 56 allows access to mapping tables and shows
`storage devices 60, 62 and 64 as they exist physically
`rather than as they have been allocated.
`The environment of FIGURE 3 extends the concept of a
`single workstation having locally connected storage
`devices to a storage network 50 in which workstations 58
`are prqyidad virtual local storage in a manner
`. _.,,.
`20 t~t \o workstations 58. Storage router 56
`~· cen~lized control of what each workstation 58
`"
`sees as its local drive, as well as what data it sees as
`global data accessible by other workstations 58.
`Consequently, the storage space considered by the
`workstation 58 to be its local storage is actually a
`partition of a physically remote storage device 60, 62 or
`64 connected thr~ugh storage router 56. This means that
`ail'llilar requests from workstations 58 for access to their
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`local storage devices produce different accesses to the
`storage space on ~torage devices 60, 62 and 64. Further,
`no access from a workstation 58 is allowed to the virtual
`local storage of another workstation 58.
`The collective storage provided by storage devices
`60, 62 and 64 can be block allocated by programming means
`within storage router 56. To accomplish this function,
`atorage router 56 can include routing tables and security
`controls that define storage allocation for each
`workstation 58. The advantages provided by i1nplementing
`virtual local storage in centralized storage devices
`include the ability to do collective backups and other
`collective administrative functions more easily. This is
`accomplished without limiting the performance of
`workstations SS because storage access involves native
`low level, block protocols and does not involve the
`overhead of high level protocols and file systems
`required by network servers.
`FIGO&B 4 is a block diagram of one embodiment of
`'
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`at~. J:OUter 56 of FIGCRE 3. Storage router 56 can
`~ ~ ~·-;~ Channel controller 80 that interfaces
`with Pibre Channel 52 and a SCSI controller 82 that
`interface• with SCSI bus 54. A buffer 84 provides memory
`work space and is connected to both Fibre Channel
`controller 80 and to SCSI controller 82. A supervisor
`unit 86 is connected to Fibre Channel controller so, SCSI
`controller 82 and buffer 84.
`supervisor unit 86
`comprises a microprocessor for controlling operation of
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`storage router 56 and to handle mapping and security
`access for requests between Fibre Channel 52 and SCSI bus
`
`54.
`
`FIGURE 5 is a block diagram of one embodiment of
`data flow within storage router 56 of FIGURE 4. As
`shown, data from Fibre Channel 52 is processed by a Fibre
`Channel (PC) protocol unit 88 and placed in a FIFO queue
`90. A direct memory access (DMA) interface 92 then tllkes
`data out of FIFO queue 90 and places it in buffer 84.
`Supervisor unit 86 processes the data in buffer 84 as
`represented by supervisor processing 93. This processing
`involves mapping between Fibre Channel 52 and SCSI bus 54
`and applying access controls and routing ~unctions. A
`DMA interface 94 then pulls data from buffer 84 and
`places it into a buffer 96. A SCSI protocol unit 98
`pulls data from buffer 96 and communicates the data on
`SCSI bus 54. Data flow in the reverse direction, from
`SCSI bus 54 to Fibre Channel 52, is accomplished in a
`reverse'~• ..
`
`. ,~· ··~~e router of the present invention is a
`br~1f.~io._ that connects a Fibre Channel link directly
`to a SCSI bu• and enables the exchange of SCSI command
`set information between application clients on SCSI bus
`devices and the Fibre Channel links. Further, the
`storage router applies access controls such that virtual
`local storage can be established in remote SCSI storage
`devices for workstations on the Fibre Channel link.
`In
`one embodiment, the storage router provides a connection
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`for Fibre Channel links running the SCSI Fibre Channel
`Protocol (FCP) to legacy SCSI devices attached to a SCSI
`bus. The Fibre Channel topology is typically an
`Arbitrated Loop (FC_AL).
`In part, the storage router enables a migration path
`to Fibre Channel based, serial SCSI networka by providing
`connectivity for legacy SCSI bus devicea. The storage
`router c:an be attached to a Fibre Channel Arbitrated Loop
`and a SCSI bus to support a number of SCSI devices.
`Using configuration settings, the storage router can make
`the SCSI bus devices available on the Fibre Channel
`network as FCP logical units. Once the configuration is
`defined, operation of the storage router is transparent
`In this manner, the storage
`to application clients.
`router can form an integral part of the migration to new
`Fibre Channel based networks while providing a means to
`continue using legacy SCSI devices.
`In one implementation, the storage router is a rack
`mount 0%' free atanding device with an internal power
`suPJly.
`'1'ha atorage router has a Fibre Channel and SCSI
`pic:qS,. jf-~d, detachable power cord can be used, the
`FC connector can be a copper DB9 connector, and the SCSI
`connector can be a 68-pin D type. Additional modular
`jacks can be provided for a serial port and a 802.3
`lOBaseT port, i.e. twisted pair Ethernet, for management
`access. The SCSI port of the storage router supports
`SCSI direct and sequential access target devices and
`supports SCSI initiators, as well. The Fibre Channel
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`port interfaces to SCSI-3 PCP enabled devices and
`initiators and implements •
`To accomplish its functionality, one implementation
`of the storage router uses: a Fibre Channel interface
`based on the HEWLETI'-PACKARD TACHYON controller and a GLM
`media interface; an Intel 80960RP processor,
`incorporating independent data and program memory spaces,
`and associated lcgic required to implement a stand alone
`processing system; and a serial port for debug and system
`configuration. Further, this implementation includes a
`SCSI interface supporting Fast-20 based on the SYMBIOS
`53C8xx series SCSI controllers, and an operating system
`based upon the WIND RIVERS SYSTEMS VXWORKS or IXWORKS
`kernel, as determined by design.
`In addition, the
`storage router includes software as required to control
`basic functions of the various elements, and to provide
`appropriate translations between the FC and SCSI
`protocols.
`" The •tocrage router has various modes of operation
`are ~•J,f,l• between FC and SCSI target and initiator
`~.~~ These modes are: FC Initiator to SCSI
`Target; SCSI Initiator to FC Target; SCSI Initiator to
`SCSI Target; and FC Initiator to PC Target. The first
`two modes can be supported concurrently in a
`single storage router device. The third mode can involve
`two storage router devices back to back and can serve
`primarily as a device to extend the physical distance
`beyond that possible via a direct SCSI connection. The
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`last IDOde can be used to carry PC protocols encapsulated
`on other transmiesion technologies (e.g. ATM, SONET), or
`to act as a bridge between two PC loops (e.g. as a two
`port fabric).
`The FC Initiator to SCSI Target mode provides for
`the basic configuration of a server using Fibre Channel
`to communicate with SCSI targets. This mode requires
`that a host system have an PC attached device and
`associated device drivers and software to generate SCSI-3
`FCP requests. This system acts as an initiator using the
`storage router to ~ommunicate with SCSI target devices.
`The SCSI devices supported can include SCSI-2 compliant
`direct or sequential access (disk or tape} devices. The
`storage router serves to translate command and status
`information and transfer data between SCSI-3 FCP and
`SCSI-2, allowing the use of standard SCSI-2 devices in a
`Fibre Channel environment.
`
`The SCSX Initiator to FC Target mode provides for·
`the cf:!ltfiguration of a server using SCSI-2 to communicate
`This mode requires that a
`host system h&a a SCSI-2 interface and driver software to
`control SCSI-2 target devices. The storage router will
`connect to the SCSI-2 bus and respond ae a target to
`multiple target IDs . Configuration information is
`required to identify the target IDs to which the bridge
`will respond on the SCSI-2 bus. The storage router then
`translates the SCSI-2 requests to SCSI-3 PCP requests,
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`allowing the use of FC devices with a SCSI host system.
`This will also allow features auch as a tape device
`acting as an initiator on the SCSI bus to provide full
`support for this type of SCSI device.
`The SCSI Initiator to SCSI Target mode provides for
`the connection of a SCSI-2 initiator to a set of SCSI-2
`targets over a PC link. Thi• allows for extending the
`distance over which SCSI-l device• can cOIDmunica.te. This
`can involve using two storage routers connected together
`on the PC port, with one storage router connected on the
`SCSI-2 side to a SCSI-2 initiator, and the other storage
`router configured as a SCSI-2 initiator, with target
`devices attached. The storage router translates the
`SCSI-2 requests to SCSI-3 FCP, and transfers them to the
`remote storage router, where they are translated back to
`SCSI-2.
`It may be desirable to bypass conversion of the
`SCSI· requests and use a direct data connection to
`.encapsulate and transfer SCSI information. This would
`allow for a broader range of compatibility with existing
`scst 4-Vices. The storage router could .be configured to
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`made, and automatically enter this mode of operation.
`The PC Initiator to FC Target mode may involve
`replacing the SCSI-2 interface with other interfaces,
`providing bridging or data forwarding over other
`technologies. Back to back implementations could provide
`FC-AL connectivity in WAN environments. Poasibilities
`include IP/IPX bridging (Multiple protocol routing) from
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`FC-IP to Ethernet, Token Ring, ATM, FDD!, etc. This
`would provide FC subnets a method to interoperate with
`
`other networking technologiee, and would be a require~ent
`if PC is to be used as a LAN technology. The specified
`hardware architecture should allow for this by
`substituting the appropriate hardware for the SCSI-2
`interface. Another possibility i• PC data encapsulation
`on ATM, BONET, or other high speed protocol. This would
`allow distance isolated FC loops to communicate via wide
`area networking or other point to point high speed link.
`Again, the hardware architecture should support this by
`
`substituting· the appropriate interface for the SCSI-2
`interface. Software changes may include driver code for
`
`the interface, and appropriate code to encapsulate the FC
`state and data to be transferred.
`In general, user configuration of the storage router
`will be needed to support various functional modes of
`operation. Configuration can be modified, for example,
`t~ a -.rial port or through an Ethernet port via
`
`~· ·~~~~~:aetwork management protocol) or a Telnet
`~·. ··~ifically, SNMP manageability can be
`provided via An 802.3 Ethernet interface. This can
`provide for configuration changes ae well as providing
`statistics and error information. Configuration can also
`be performed via TELNET or RS-232 interfaces with menu
`driven command interfaces. Configuration information can
`be stored in a segment of flash memory and can be
`retained across resets and power off cycles. Password
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`protection can also be provided.
`In the first two modes of operation, addressing
`inforlll&tion is needed to map from FC addressing to SCS!
`addressing and vice versa. This can be 1 hard 1
`configuration data, due to the need for address
`information to be maintained across initialization and
`partial reconfigurations of the Pihre Channel addreas
`apace.
`In an arbitrated loop configuration, user
`configured addresses will be needed for AL_PAs in order
`to insure that known addresses are provided between loop
`
`reconfigurations.
`With respect to addressing, FCP and SCSI 2 systems
`employ different methods of addressing target devices.
`Additionally, the inclusion of a storage router means
`that a method of translating device IDs needs to be
`
`In addition, the storage router can respond
`implemented.
`to commands without passing the commands through to the
`opposite interface. This can be implemented to allow all
`941~¥"ic ~'pd SCSI commands to pass through the storage
`~"t.o ~ss attached devices, but allow for
`. . .. t•t~~~d diagnostics to be performed directly on
`.....
`the storage router through the FC and SCSI interfaces.
`Management commands are those intended to be
`processed by the storage router controller directly.
`This may include diagnostic, mode, and log commands as
`well as other vendor-specific cotmnands. These commands
`can be received and processed by both the FCP and SCSI
`interfaces, but are not typically bridged to the opposite
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`interface. These commands may also have side effects on
`the operation of the storage router, and cause other
`storage router operations to change or terminate.
`The primary method of addressing management commands
`though the FCP and SCSI interfaces can be through sec
`peripheral device type addreasing. For example, the
`storage router can respond to all operations addressed to
`logical unit (LON) zero •• a controller device. Commands
`that the storage router will support can include INQUIRY
`as well as vendor-specific management commands. These
`are to be generally consistent with sec standard
`commands.
`The SCSI bus is capable of establishing bus
`connections between targets. These targets may
`internally address logical units. Thus, the prioritized
`addressing scheme used by SCSI subsystems can be .
`represented as follows: BUS:TARGET:LOGICAL UNIT. The BUS
`identification is intrinsic in the configuration, as a
`SCSI ini$;i~ is attached to only one bus. Target
`addl'e••i.DI' i.e handled by bus arbitration frora information
`~ided :t~~t\t. arbitrating device. Target addresses are
`assigned to SCSI devices directly, though some means of
`configuration, such as a hardware jumper, switch setting,
`or device specific software configuration. As such, the
`SCSI protocol provides only logical unit addressing
`within the Identify message. Bus and target information
`is implied by the established connection.
`Fibre Channel devices within a fabric are addressed
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`by a unique port identifier. This identifier is assigned
`to a port during certain well-defined states of the FC
`protocol.
`Individual ports are allowed to arbitrate for
`a known, user defined address.
`If such an address is not
`provided, or if arbitration for a particular user address
`fails, the port is assigned a unique address by the FC
`protocol. This address is generally not guaranteed to be
`unique between instances. Various scenarios exist where
`the AL-PA of a device will change, either after power
`cycle or loop reconfiguration.
`The FC protocol also provides a logical unit address
`f