Published by ArticulatePresenterwww.articulate.com Published by ArticulatePresenterwww.articulate.com Notes:Welcome to the Fibre Channel Fundamentals for Tape Drives training session. This module should take about 60 minutes to complete. Notes:This course covers the fundamental concepts of Fibre Channel as used with tape drives that support this protocol. These include Oracles StorageTek T9840A, B and C, the T9940B, and the T10000 drives.Other vendor tape drives that support Fibre Channel are HP and IBM LTO drives, and the Quantum SDLT 600 and DLT-S4 models. We will briefly look at the background and architecture of Fibre Channel and how the architectural layers are structured. The hardware components are discussed, and we will look at node and port identification in a Fibre Channel network. The frame structure used to transfer data using these components in frequently used topologies will also be illustrated. This course does not cover in depth Fibre Channel specifications or troubleshooting. Published by ArticulatePresenterwww.articulate.com Notes:In the late 1980s IBM introducedfiber optic cabling into the computer data center and network. This technology has many advantages and it was considered to be the most significant improvementto the I/O area in twenty-five years. Fiber optic cables provide larger bandwidth, with fewer losses during signal transmission. Unlike copper cables, fiber cables produce little or no crosstalk.These connections provide physical advantages of being much lighter and smaller, which make installation easier. Speeds of up to 8 and 10 Gbit per second are already available on Fibre Channel, although tape drives are currently capable of up to 8 Gbit per second speeds. The need to connect more and different types of devices gave rise to the development of the Fibre Channel standard. This is a protocol constructed of four main layers, the fourth or upper layer,being the layer which maps to a variety of protocols. Notes:Fibre Channel is structured as a set of hierarchical functionswith the lowest level known as FC-0, and the upper level as FC-4.These levels are defined as follows: FC-0 Defines the physical link in the system, including the fiber, connectors, and associated optical and electrical parameters supporting a variety of data rates.FC-1 Defines the transmission protocol, the encoding and decoding of data for transmission, as well as error detection and clock recovery. FC-2 Defines signaling and framing protocols, frame content, headers and trailers. FC-3 Defines commonnode services such as hunt groups, striping or multi-cast. FC-4 Specifies the mapping rules of upper level protocols or ULPs, using the lower FC levels. Fibre Channel is equally adept at transporting both network and channel information and it allows both protocol types to be concurrently transported over the same physical interface. We will look at these upper level protocols next. Published by ArticulatePresenterwww.articulate.com Notes:There are four defined channel protocols. They are: Intelligent Peripheral Interface or IPI Small Computer System Interfaceor SCSI, pronounced scuzzy the ANSI standard is called FCP-3. Where SCSI is used as the ULP, it is commonly referred to as FCP High Performance Parallel Interfaceor HIPP) Framing Protocol Single Byte Command Code Set Mapping or SBCCS. This is the underlying command set for both ESCON and FICON. Three network protocols are defined, the IEEE 802.2 protocol, Internet Protocol (IP), andATM Adaptation Layer for computer data.This layered organization is useful to us in a number of ways.When we look at the devices that have been developed based on this standard, this model serves as a useful tool to understand what purpose a particular device serves. It also serves to help us understand what the capability of a particular device is.A device that is described, for example, as an FC layer 1 devicewould not be capable of directing frames to particular addresses because the addresses arewithin the FC frames: the device would have to be capable of FC-2 functions to look inside the frame and find an address Notes:The FC standard does not describe specific pieces of hardware, only the components capability to provide valid connections and services. In general, open systems servers have appropriate HBAs installed that are connected either to switches, hubs, or directly to a device such as a tape drive.The connecting devices have transceivers installed to which the cables connect. Transceivers can be one of two types: the SFP, which is a pluggable, hot-swappable unit, or the SFF, which is a transceiver soldered to the interface board. GBICs or Gigabit Interface Converters are the connectors used on1-Gigabit/sec-capable drives connected to matching host HBAs. They are still found in many data centers although newer equipment uses SFPs or SFFs on2 and 4-Gbit/sec interfaces. Mainframe computers use I/O processors that drive channel cards. These could be ESCON channels or FICON channels. Newer mainframes would support a mix of both, depending on customer requirements.Mainframe channels that can be either ESCON or FICON capable can connect to ESCON or FICON directors. Published by ArticulatePresenterwww.articulate.com Notes:The Fibre Channel specification combines the strengths of channels, with those of networks, including flexibility and long distance capability.To maximize a tape drives data throughput, the Fibre Channel network has to be built with the appropriate components.Hosts need to have Host Bus Adapters installed from where fiber cables are connected to some network device, such a Fibre Channel switch, a hub, or a director. In turn, the network devices are connected to the ports on the tape drive.Depending on the tape drive model and the customer requirements for configuration, only the A port, or both the A and B ports can be connected. The second port is usually only connected for redundancy or wider connectivity. Once the Fibre Channel network has been built, the drive uses its World Wide Node Name or WWNN and World Wide Port Names to log in to the network device. The HBA installed in the host server must log in to the network as well to establish communication with the tape drive.Once all devices have logged in, the host server can begin tape operations.SCSI commands, packaged into frames, are used to communicate on the fiber network.A frame is a container of information sent on a SCSI Fibre Channel network. The frames of information are sent as light pulses or optical signals.Commands issued by the host direct the drive, for example, to send status information or to read and write customer data. Notes:Once all the links are established and the Fibre Channel network is functional as described in the previous slide, data transfers can take place. Sustained data flow to and from tape drives is controlled using a mechanism known as Buffer-to-Buffer-Credits, or BB-credits. BB-credits represent the number of buffers supported by a Fibre Channel porton a node for receiving frames. These parameters are discovered by the attached devices during the login process after they power on. The login process is discussed in a later slide. The protocol chip used on the device interface determines the size of the buffer. As an example, the T10000A 2-Gbit/sec tape drives use a protocol chip that supports three BB-Credits. The 4-Gbit T10000A tape drive uses a protocol chip and an inline extender chip that supports 602 BB-credits. Vendors use different chips on different types and models of equipment, providing different values of BB-credits depending on the trade-offs they make between the physical size of the chip, compared to the buffer size and complexity. Qlogic 4-Gbit HBAs, for example, use three BB-credits. Published by ArticulatePresenterwww.articulate.com Sustainable performance for tape drives over longer distance is better when devices with more BB-credits are used. When operating at about 1 kilometer or less, at 4-Gbit/sec Fibre Channel rate, three BB-credits are sufficient to sustain performance and not cause degradation.Having a larger BB-credit than needed just means there will be unused buffer space, but having too few buffer credits will degrade performance. Notes:A node is a device that can send or receive transmissions in a Fibre Channel network. This could be a mainframe, server, or workstation and it is known asthe host node. The adapter or interface card converts electrical signals to optical signals, or light pulses, for transmission over the fiber cables. Disk drives, disk arrays, or tape drives could be the node at the other end of the link. A node has at least one port, but might have more. Oracle FC tape drives support two ports. Even in tape drives that have two ports, only one is ever active at any given time. If both are connected one is usually the primary port and the other acts as a backup. Each device has a unique 64-bit World Wide Node Name, abbreviated to WWNN, which is also simply known as the node name. The node name is set at the factory. We will look at the structure of the WWNN in a later slide. Notes:A port is a Fibre Channel access point where a fiber-optic cable or transceiver plugs into a device.Ports are full duplex, capable of sending and receiving signals simultaneously. HBAs have one or more ports. The Oracle StorageTek Fibre Channel tape drives support two ports port A and B.Each port connects to two fibers, one for transmitting and one for receiving data. Tape drives, however, do not operate in full duplex mode. Each port has a unique 64-bit World Wide Port Name or WWPN set at the factory, and each node has a World Wide Node Name or WWNN. Different port types are identified in a later slide. Published by ArticulatePresenterwww.articulate.com Notes:Each node has a unique World Wide Node Name or WWNN.This is a 64-bit number, usually represented as eight two-digit hex numbers. This node name is similar in concept to the MAC address of a network interface card. The World Wide Node Name also identifies the company with a vendor specific identifier. Each port has a unique World Wide Port Name or WWPN by which it is identified. Notes:In Ethernet networks, devices are identified by a unique media access control or MAC address. In Fibre Channel networks, HBAs and other Fibre Channel devices, also use a unique identifier. This is the World Wide Name or WWN. These names are also known as World Wide Node Names and World Wide Port Names. A WWPN is presented when a device port logs into a fabric or SAN. WWNs consist of 16 hexadecimal digits grouped as eight pairs. These are written with a colon separating each pair for example, 50:01:04:FB:17:34:F6:2D. The format of the WWN is defined by the IEEE. The first digit indicates the format that the particular WWN has and is defined by the NAA. Oracles StorageTek products use the number 5 in the NAA field, bits 60-63 of the WWN.Format 5 enables vendors to create unique identifiers without having to maintain a database of serial number codes.This format is mostly used by hardware vendors to create unique WWN values based on serial numbers and physical port numbers. The format has three sections as illustrated in the slide. Section 1 identifies this as a registered name WWN the NAA. Section 2 identifies the vendor. Currently, Oracle StorageTek uses 00104f as the company identifier. Reading the bits from left to right, this would be bits 59 through 36. Section 3 is a vendor-specific identifier or VSID. In this particular format, the hardware vendor uses a complex algorithm to generate this part of the number represented by bits 35 through 00. Sections 1 and 2 should never be altered; these numbers are fixed. Published by ArticulatePresenterwww.articulate.com Notes:Default World Wide Node and Port Names are set by manufacturing. The Fibre Channel tape drives default addresses can be changed manually to a custom World Wide Node or Port Name by service personnel using operator panels or service tools appropriate to the drive type. When tape drives are installed in a library, it is possible that the World Wide Names can be dynamically overridden by the library. The dynamic library addressing feature is implemented to correct reconfiguration problems within a Fibre Channel network. If a Fibre Channel device with a fixed WWN in a network were to be replaced, it would be detected as unknown because of the new WWN.Some reconfiguration of the network would be needed to make this drive available. However, when enabled, dynamic world-wide naming assigns names to library drive slotsrather than to specific tape drives. Therefore, when a drive is replaced in a library, the new drive receives the same name as the one replaced, thereby eliminating the need for system reconfiguration. The SL8500 library software automatically overrides any previously assigned WWNs in the drive.The L700/180 and 1400 libraries can be configured to set dynamic WWNs. SL3000 supports DwwnThe 9310 library cannot be configured to set dynamic WWNs. Notes:A link is described as a full duplex link because it supports simultaneous two-way communication. Although Fibre Channel is capable of full duplex communications, this is not used with tape drives.A link is established when two fiber ports that transmit and receive signals through a fiber-optic cable are connected.Links between devices and servers include HBAs, fiber-optic cables, and fixed or pluggable transceivers. Transceivers, SFPs or SFFs, are available with a variety of different transmitter and receiver types. You need to match the optical cable type to the SFP or SFF type. Optical signals are generated by the connected devices using either laser or LEDs as the light source. Published by ArticulatePresenterwww.articulate.com Notes:Tape drives with 2 or 4-Gbit/sec FC interfaces use fiber-optic cables with male LC connectors. The transceiver module in the tape drive, HBA, or switch, has a female LC connector. LC stands for Lucent Connector or Local Connector.This is a small form-factor fiber-optic connector that uses a 1.25-millimeter ceramic ferules to correctly position the optical fiber. The connector has a latch mechanism to secure it when it is plugged into the tape drive, HBA, or switch.The LC connector is approximately half the size of an older SC connector. SC stands for Standard Connector or Subscriber Connector. The SC connector is a fiber-optic connector with a push-pull latching mechanism that provides quick insertion and removal, while also ensuring a positive connection. SC connectors are mostly used for 1-Gbit/sec interface connections. If needed, adapter cables are available to convert from a male SC to a male LC. To limit damage and contamination, cables are shipped and stored with protective caps over the ceramic ferules. Notes:Fiber-optic cable cores can be constructed of glass, plastic or plastic-clad silica or PCS. Glass core cables have the lowest attenuation or (signal losses) and are most widely used. Plastic core cables have the highest attenuation, while the PCS cables attenuation is somewhere between that of glass and plastic. Multi-mode fiber-optic cable is used to transmit a short wave length 850nm red laser light. This light is visible but damaging to the naked eye.A central glass core is 50 microns wide, surrounded by an outer glass cladding, 125 microns wide. The boundary between these layers of glass acts as a mirror. The light travels down the fiber by bouncing (being reflected) from one side of the fiber to the other for the length of the fiber.Not allthe light enters the fiber atthe same angle, hence it does nottake the same path as it bounces down the fiber. This is why this type of fiber is called multi-mode; the light can take multiple modes or paths as it travels down the fiber. As all the light travels at the same speed, the light taking the most direct route arrives at the other end first, and light taking a longer route arrives later. As you can imagine, as the fiber gets longer, eventually the fast light (taking the most direct route) of one bit will catch up withthe slow light (longer route) fromthe previous bit. This smudging of one bit and the next is called dispersion, and limits the reliable length of multi-mode fibers.It is important to select a cable length that is compatible with the data throughput rate of the drive. Using 50-micron multi-mode fiber at 4 Gigabit per second throughput rates supports cable lengths up to 150 meters. Choosing this cable size and length will take advantage of, for example, the T10000 Published by ArticulatePresenterwww.articulate.com tape drives high throughput levels. Notes:A longer wave length, infrared light is used with single mode fiber cables. The fiber used ismuch narrower, 9 microns, and it is constructed like a lens. The narrow and lens-like fiber has only one path (or mode) of light traveling down the fiber. So, dispersion is not a problem with single mode fibers; the only limit to the length of cable is the clearness of the fiber and the brightness of the laser.Lasers and single mode fiber-optic cables are capable of 1, 2, and 4-Gbit/sec throughput rates over distances of 10 kilometers or more.Lasers and fiber capable of 10 kilometer distances are a Fibre Channel standard. However, it is possible with combinations of purpose-designed components to increase that distance. Notes:The fiber cabling must follow the guidelines shown on the slide to produce reliable performance results.The Fibre Channel link nodes need to have the same transceiver types. For example, a short-wave-length transceiver at the switch, needs to be matched with a short-wave-length transceiver at the drive port.The fiber optic cable type has to be the same within a link. For instance, if a single mode cable is used, all the components such as patch panels and jumpers between the switch port and the drive port need to be the same.This is an easy mistake to make in cases where adapter cables are used. However, the cable from the switch to host can be the same or different than the drive link.In general, it is recommended to use 50-micron cables when connecting tape drives. The reason for this is that some tape drives have a stub-cable built in that connects the outer connector to the interface card. This stub cable is a 50-micron cable.If you were to connect a 62.5-micron cable to the drive, the incompatibility between the cable you connect and the 50-micron interior cable would causeproblems. Published by ArticulatePresenterwww.articulate.com Notes:This slide illustrates an IBM drive in an SL500 library drive tray. Notice that only port A is installed and cabled. The figure on the right illustrates the 50-micron stub cable that is installed to connect the port on the outside of the tray to the drive. It is important to connect a 50-micron cable to match the cable internal to the tray. Notes:This slide illustrates an SL8500 library drive tray with an HP LTO drive installed. Viewing the tray from the rear, you can see that only port A is installed. Published by ArticulatePresenterwww.articulate.com Notes:In this slide you can see that the T10000 drive has SFPs installed for both the A and B ports, but it has only port A connected. On the right, an HP LTO drive is shown, also with only port A connected. Because tape drives are not capable of executing concurrent operations on both interfaces, the B port is frequently not connected. Notes:This slide illustrates the L700 library drive tray with a DLT-S4 drive installed. Notice that only port A is installed and cabled. Notes:Once the physical network has been built and the tape drive and other network devices have completed their login, the network is ready to begin tape operations.The network uses Fibre Channel protocols to govern how the communication takes place between devices on the network. The devices connected to the network determine which of the Upper Layer Protocols mapped in the FC-4 layer are used.FCP (the SCSI Fibre Channel protocol) uses the terminology of initiators (the communication sender) and targets (the communication receiver).The tape operation communication process is facilitated by the initiator transmitting commands and data, and the target transmitting response statusor data back to the initiator. The process of logging into the fabric is discussed in the slides dealing with topologies. Published by ArticulatePresenterwww.articulate.com Notes:The concept of drive Reservation is used to ensure that a host could not try to use a tape drive while it is in use by a different host. Reservation of the tape drive process is not a requirement, as long as no other hosts would try to use it while another host is already using it.When the host application is ready to start using a tape drive, it should reserve it if it can, or wait until it becomes available. Once it is done using the tape drive, it should release it, so another host would be able to use that drive.The process of reserving and releasing the drive can use the older commands of Reserve Unit (16h/56h) and Release Unit (17h/57h) or the newer commands of Persistent Reserve Out (5Fh) and Persistent Reserve In (5Eh).This newer method expands the capabilities of reserving the drive with keys between multiple hosts, doing third-party reservations.Persistent Reserve In returns information about existing keys, reservations, and so on. Some of the actions of the Persistent Reserve Out command are to register the keys and reserve the device. These reservations do not get cleared on certain types of tape drive reset operations where as the older reservation method does get cleared. Notes:Datatransmission occurs when an N(x)_Port receives Data frames from other N(x)_Ports and transmits the appropriate Link_Control responses for those frames to the proper N(x)_Ports. An N(x)_Port may operate according to these communication models: 1. Simplex operation is defined as an N(x)_Port transferring Data frames in one direction only, with Link_Control frames flowing in the opposite direction; 2. Full-duplex operation is defined as an N(x)_Port simultaneously transmitting and receiving data frames, with Link_Control frames flowing in both directions as well. c) Half-duplex operation is defined as an N(x)_Port both transmitting and receiving data, but not simultaneously. Data frames and Link_Control frames flow in both directions, but the flow is limited to a single direction at a time. For example, if you were to have a host running two applications, one reading from a particular tape drive, and the other application writing to a different tape drive, the host HBA would be operating in true full duplex mode. Each individual tape drive only operates in half-duplex mode, with each host application. Tape drives are designed as nonqueued SCSI devices, or in reality a queue depth of one, with the host logged into each drive.The following slide illustrates how the data and commands are packaged for transmission. Published by ArticulatePresenterwww.articulate.com Notes:As stated earlier, the communication between the host and a tape drive across the network uses the FCP3 protocol. This protocol dictates that Fibre Channel communications are constructed using exchanges, sequences, and frames.An exchange represents a logical operation such as a read or write. An exchange groups together sequences that share a unique identifier.A sequence represents groups of frames, forming commands, data transfers or status and responses. All sequences within a given exchange use the same protocol.Sequences are a series of frames strung together in a numbered order that can be transmitted over a Fibre Channel from one port to another port as a single operation.Frames are a linear set of transmitted bits that define the basic transport unit. The structure of a frame is shown in the next slide. Note that different manufacturers HBAs communicate or multiplex at different levels. For example, Qlogic communicates at the Exchange level, which means it has to complete the transmission of all the sequences and frames within that exchange before it can start a new transmission. Emulex, on the other hand, communicates at the frame level. Notes:The frame is the most basic element of a message in Fibre Channel communications. A frame is defined as an indivisible, encapsulated data structure containing a start-of-frame or SOF and an end-of-frame or EOF designator and carrying a payload of both control data and user data from one Fibre Channel port to another.The primary function of the Fibre Channel network is to receive the frames from the source portor sender, and route them to the destination port or receiver.Each frame begins with the frame delimiter, Start of Frame, and ends with theEnd of Frame delimiter. Both are 4 bytes in length. Published by ArticulatePresenterwww.articulate.com Notes:This slide illustrates the data portion contained in a frame. The host initiates the write operation for the tape drive to write data to tape.The drive removes the payload information from the data frame and records it to tape in block format.The other sections of the data frame are not recorded on tape, they are only used for routing the data frame between the tape drive and the host.When a read operation is initiated, the data is read in blocks by the drive from tape. The drive assembles the data blocks into the data frame payload section, adds SOF, Header, CRC, and EOF frame information for transmission back to the host. Notes:Users create files on a host that contain their data. The examples in the slide are files such asLetter.doc, Program.exe, and Another.doc.Host operating systems manage these files by placing them in directories.If the files generated by the user need to be saved to tape during backup operations, the host server converts these files to data frames for transmission to the tape drive. The data frames payload section contains the file data translated into block format.The tape drive records and stores the files in block format on tape. The tape drive also maintains a directory of blocks recorded on tape. A read operation ofthese files causes the tape drive to read the blocks of data, assemble the data into data frames that are part of a sequence in an exchange, and send that to the host. Notes:The Header is six 4-byte words, and it contains fields that include identification and controlinformation.These fields are: R_CTL Routing control: Indicates the type of frame functions. Destination ID Identifies the destination port (the 24-bit address) for the frame.CS_CTL Class-specific control field. Source ID Identifies the source port sending the frame.Type Indicates the data structure. F_CTL Frame Control: Controls information within the frame. SEQ_ID Sequence Identifier: Identifies sequences within an exchange. DF_CTL Data Field Control: Indicates optional headers.Published by ArticulatePresenterwww.articulate.com SEQ_CNT Sequence Count: Contains frame number within exchange.OX_ID Originator Exchange ID: Identifies originator of the exchange.RX_ID Responder Exchange ID: Identifies responder tothe exchange.Parameter Contains unique parameters for exchange Notes:In a previous slide we saw that the maximum block size setting of the tape drive determines the size of the data frames in an exchange. A simple equation would be to say that the larger the block size, the better the sustainable transfer rate would be. However, there are many other factors that all have some influence on how well a tape drive performs. On the tape drive side, one has to consider items such as the Fibre Channel protocol chip used in the designwhat is the speed of the processor and how large is the buffer? Different tape drives have different internal data transfer rates and data compression algorithms and they also format the tape differently. Tape drive media speed also play a role in determining the performance, that is, how fast is the data written to the tape. From the host side, there are also many influencing factors, such as the host CPU power and the PCI bus structure. The host HBA has a defined number of buffer credits that might or might not be enough to sustain transfer to the tape drive. The Fibre Channel operating rate of the HBA could be 1, 2 or 4 Gbit per second. If this is slower than the tape drive is capable of, the full potential of the tape drive is not used. Fibre Channel switches could pose similar issuesthe architecture and hardware capability needs to be taken into account, as well as their port BB-credits. Finally, cable lengths need to be consideredthis could range from 1 meter to 10 kilometers and would influence transfer rates. Published by ArticulatePresenterwww.articulate.com Notes:In the next few slides we will look at port types and at three possible topologies for Fibre Channel connections.A Fibre Channel topology is a type of network that connects two or more node ports. The topology includes software, hardware, and firmware of the devices included in the network.There are three general types of Fibre Channel topologies: Fabric, Arbitrated Loop, and Point-to-point.A fabric, or switched fabric topology is frequently used, and it incorporates Fibre Channel switches and or Fibre Channel directors. Notes:Fibre Channel networks use different port types: N_Ports for switched fabric and L_Ports for loop networks. Switches use FL_Ports if connected in an arbitrated loop, and F_Ports when connected to a fabric. N_Ports are Fibre Channel ports that are not on a switch and are not functioning in loop mode.They may be connected point-to-point or from the node to anF_Port on a switch. Ports that work on both loop and switched networks are called NL_Ports.Fibre Channel tape drives have NL ports that are fabric aware so they can function as eitherN_Ports or NL_Ports.Hubs are devices with a number of NL Fibre Channel ports. If a functioning NL_Port is connected to a hub, then that port is included into the loop. While hubs have Fibre Channel ports, hubs serve as links and are notactive nodes.A hub cannot decode orlook insidea frame that it receives or transmits. Neitherdoes a hub understand addressing. Hubs tend to come in two types: unmanaged or dumb, and managed. The latter can provide a range of features from management and support of multiple loops to SNMP error reporting. Published by ArticulatePresenterwww.articulate.com Notes:A fabric network consists of nodes connected to a switch, a group of interconnected Fibre Channel switches, and/or Fibre Channel directors.Switches and directors maintain a database of the addresses of devices connected to each port on the switch.Switches and directors provide dynamic interconnection of all nodes in a fabric and for interconnection with other switches to extend the fabric.Fabric devices use the destination address of the drive to determine the path from the host through the fabric to the drive. Notes:There are two types of Fibre Channel fabric switching devices: directors and switches. Directors are mostly used in MVS or mainframe environments; switches are usually used in open systems or UNIX, Windows, and Linux environments. Directors are more capable (and more expensive) than switches. The director provides dynamic switched connections for servers and devices. They support both mainframe and open-systems interconnection (OSI) computing environments.They also provide data transmission and flow control between device node ports (N_Ports). Through interswitch links (ISLs), a director can also connect to one or more additional directors to form a Fibre Channel multi-switch. Switches could be as small as eight ports and range up to 32 or 64 ports or more, depending on vendors and models. Switches provide ports of low-cost and high-performance dynamic Fibre Channel connectivity for switched fabric devices or arbitrated loop devices. A switch, unlike a hub, can use zoning to isolate groups of devices from each other. Zoning applies only to a switched fabric topology. Published by ArticulatePresenterwww.articulate.com Notes:Fabric Login: The nodethis case, the N-port of a tape drivesends a FLOGI frame to the address of XFFFFFE of the switch. This is the address of the Login Handler function of the attached switch.The login handler controls addresses allocated to Fabric nodes and thus ensures that all port addresses on this Fabric are unique. The login handler replies to the FLOGI requests with anAccept (ACC) frame. The N_Port specifies its source address in the FLOGI frame as x000000 when sending the frame to the xFFFFFE port. This tells the login handler that it is an N_Port logging in.TheAccept (ACC) sent by the handler is sent to the address the handler is allocating to the N_Port.The assigned address is derived from the switch (domain field), port on switch (area field) and usually 00 for the port field.A later slide demonstrates the login sequence in a disk-to-disk-to-tape fabric configuration. Notes:Simple Name Server or SNS is a switch function that maintains a database of devices connected to the fabric. One important function of the SNS is to map the device WWN to an address assigned by the switch. It allows nodes to register details such as their port name, WWNs, and capabilities. To register its information, each port on the Fabric sends a Port Login frame or PLOGI to a fabric address, xFFFFFC. After a tape drive logs in to the switch, it waits for the host initiators on the fabric to complete a Port Login, and aProcess Login or PRLI before starting tape operations.HBAs can register and query the SNS while tape drives can only register.For example, an HBA could query the SNS to determine which ports on the Fabric support FCP. The SNS in Fibre Channel switch is also used to discover the World Wide Names of devices connected to the switch. Published by ArticulatePresenterwww.articulate.com Notes:After devices that are connected to a fabric power on, a sequence of events occurs to enable them to communicate. In the absence of a loop environment, the Oracle StorageTek tape drives NL_Port attempts to initialize with a fabric. This is accomplished by doing a Fabric Login.The FLOGI process is attempted in each class of service that the tape drive supports. Once the FLOGI process is successful, the tape drive attempts to log in, a Port Login, (PLOGI) with the fabric-attached name server, if it exists. This process allows the tape device to register its presence with the name server such that initiators may query the name server to find target tape drives to use. The tape drive now waits for initiators on the fabric to complete a Port Login and a Process Login and then to start executing tape commands. Notes:The Fibre Channel Switch Fabric uses a 24-bit address for each port.The 24 bit address has three portions, the Domain, the Area and the port.Each portion uses 8 bits of the 24 bit address. Domain The Domain portion of the address is used to identify the switch. Some address values are reserved, but there are 239 availableswitch addresses. This would allow 239 switches to be connected together into a fabric.Area The Area portion is used to identify the port on the switch or a sub-area of a switch called a blade. This allows switches to have 256 ports or more if they use these sub-areas called blades. Sub-areas would be used more by Directors that have a large number of ports. Port The Port portion of the address is either set to 00 in the case of an N_Port directly connected to the switch (F port) or this field could alternatively be used for the Arbitrated Loop Physical Address (AL_PA) of the devices attached to an arbitrated loop connected to the switch.Note: This section is how Brocade switches implements the Area & Port standard .Cisco implements the Area & Port standard differently. Published by ArticulatePresenterwww.articulate.com Notes:The power-on initialization sequence of devices in a fabric solution is important because it affects the addressing of attached devices. Oracle recommends you power on the switch first because the switch name service logs in devices on a first-come first-served basis.To guarantee order in the name service, the device logins must be controlled in sequential manner.Next, power on the library so that it can provide a dynamic World Wide Name to the drives, if this feature is enabled.If the drives were not powered on by the library, they should be powered on next. Thetape drives log in to the switch.Power on the servers last. Each HBA installed in the server performs a login to the switch and then queries the simple name service, which then returns the available devices to the HBA.Each HBA performs PLOGI and PRLI to each discovered device. The HBAs assign IDs to the tape drives based on the HBA discovery scan order.If the host was powered-on, first it would not be able to exchange address information with the switch nor communicate with the drives. Therecommended power-off sequence is the reverse. Notes:Fibre Channel uses loop technology called Fibre Channel Arbitrated Loop orFC-AL. FC-AL was added to the standard to provide a low cost, shared bandwidth alternative to fabric. It was not designed to be a high-performance topology. Note that the SL8500 libraries do not support tape drives connected in a loop. The T10000 4-Gbit/sec model tape drive does not support loop topology, although the 2-Gbit/sec model does. The ports in a Fibre Channel Arbitrated Loop have the characteristics of N_Ports but with added loop functions. They are called NL_Ports.The NL_Ports are arranged in a loop, the transmit Fibre of one port goes to the receiver of another and so on around the loop. The ports have to be arranged in a loop for packets to flow around from their source to their destination.The slide illustrates the loop. A target establishes one virtual point-to-point connection with a destination at a time. Loop functions include: Retransmitting packets that have arrived but are not addressed to this port; the packet continues around the loop until it arrives at its destination. All the ports share the bandwidth. Both a public loop and a private loop is supported. When devices want to communicate on the Published by ArticulatePresenterwww.articulate.com Fibre Channel bus, they must arbitrate and win control of the loop before communications can begin.Port and loop initialization and arbitration are discussed in the next few slides. Notes:At power up, loop initialization starts. The loop initialization process or LIP is a logical procedure that establishes the Arbitrated Loop Physical Address of each port. AL_PAs are assigned values ranging in value from x01 to xEF or an equivalent Loop ID value ranging from 125 to 000.Speed negotiation is also done at this time by the attached hardware. All devices negotiate to the highest common speed. For example, a device capable of 1, 2, or 4 Gbit/sec, will run at2 Gbit/sec if there is a device in the loop that is only capable of 2 Gbit/sec. During the Loop Initialization process a loop master is chosen. This is called Loop Initialization Select Master or LISM. The loop master directs the rest of the loop initialization procedure, then closes the loop and returns it to normal operation. Oracle recommends making a host the loop master by giving it the lowest address on the loop.If another device on the loop were to be the master and it fails, the entire loop has to bere-initialized, whereas if the host is the master and some other device fails, it can just be removed or replaced.When cabling a loop, it is also important to consider that Qlogic HBAs scan addresses from 125 to 0, and Emulex HBs scan from 0-125. This is important if you want to maintain addressing order in a loop configuration. Oracle StorageTek tape drives support the process of Loop Initialization Fabric Assigned or LIFA addressing. This is used on public loops. During loop initialization, the drives NL_Port may use the previously acquired port address before attempting to acquire another port address, or, the drives NL_Port can be configured to use a hard-assigned AL_PA address.Another option is for the drive to use a soft-assigned port address. This would be used if the Hard Assigned address is not available. In any of the above, at the end of the loop initialization the NL_Portshave an AL_PA assigned. Published by ArticulatePresenterwww.articulate.com Notes:A single NL_Port needs to gain control of the loop through arbitration.Because only one device can communicate on the loop at a given time, the device must arbitrate for the loop before it can communicate with another device.When a device wins arbitration, it sends an Open Primitive Signal or OPN and completes the circuit across the rest of the loop. When the loop circuit is established, the link acts like a point-to-point connection and proceeds to PLOGI and PRLI.After all the login data is processed, the device sends a Closed Primitive Signal or CLS to open the loop for arbitration once again. That device is now ready to participate on the network. Notes:There are two types of loop topologies: a public loop and a private loop.The public loop is connected to a fabric. It employs a switch FL_portthat is able to behave as both a fabric port and a loop port. The hub in a public loop can have one port attached to the fabric, and it assumes the highest priority AL_PA, 00, or Loop ID 126.The FL_Porton the fabric acts as a gateway between the public loop and the fabric. Other nodes on the loop that are fabric-enabled can log on to the fabric and communicate with other nodes on the fabric via the gateway FL_Port. Each drive has a 24-bit address, as discussed earlier, that uses domain, area, and AL_PA values. A private loop has no connection to a fabric. Private loops are nodes that do not possess the ability to operate on a fabric. Private arbitrated loop devices only use the last 8 bits of a 24-bit address. Notes:In a private loop the drive port is identified by the address in bits 0-7. The other 16 address bits are zeroes. Published by ArticulatePresenterwww.articulate.com Notes:In a public loop the tape drive has a 24-bit address that identifies the domain, area and theAL_PA for the loop port on the device that is connected to the fabric. Notes:The point-to-point topology simply connects a host port directly to a tape drive port. TheN_Port of the host is connected to the drive NL_Port, which functions as a N_Port.An example of a point-to-point connection occurs when service personnel need to connect to a tape drive. AMAGMA box is the node or host, as it has an HBA installed. A laptop connected to the MAGMA box runs the SCSI/Fibre Toolbox software, which is used to perform service actions on tape drives. This could include loading drive firmware, downloading logs, or running diagnostic routines. Notes:After the devices in a point-to-point connection power on, they negotiate their transfer rate.Speed negotiation enables the devices to run at1,2 or 4 Gbits per second, whichever is highest common speed. The next step is link initialization. Once the two devices complete link initialization and reach the idle state, the initiator sends the Port Login command to the tape drive. PLOGI establishes the service parameters between the ports so they can communicate efficiently.Following a successful PLOGI, the initiator issues the Process Login or PLRI command and the devices can begin transferring data. Published by ArticulatePresenterwww.articulate.com Notes:In a point-to-point connection the initiator has a numerical address value. For instance, when using the SCSI/Fibre Tool Box and the MAGMA Box connected to a tape drive, the MAGMA box has an address of 1 and the tape drive has an address of 0. Notes:A configuration such as illustrated on the slide could be used where a Disk-to-Disk-to-Tape or D2D2T backup is required. In this example, the distances between the switch and the drives within the datacenter are less than 50 meters. Multi-mode cables would be used, with short wave length transceivers in the tape drives and the switch.Tape drives installed in the SL8500 library would have their default World Wide Names changed dynamically by the library. The dynamic World Wide Names would be communicated to the switch when the drives IPL and do a Fabric Loginto the switch as described on an earlier slide. The switch returns a 24-bit address to the drive, and the drive then executes a Port Login to the switch name server.When the host server powers on, the HBA would FLOGI to the switch, then PLOGI with the Simple Name Server to query for FCP devices. Then, the host would PLOGI and PRLI with each of the tape drive devices found on the switch.The devices on the fabric are now ready to communicate. During tape operations the host initiates a series of exchanges with the drive.The next slide describes the operation initiated by the host to write data to tape. The discussion does not include the library operations required to mount and dismount the cartridgeonly the host write operation sequence. Published by ArticulatePresenterwww.articulate.com Notes:When the host application opensthe target tape device for writing, it issues various Inquiry, Mode Sense, and Mode Select commands to set appropriate operation modes forthe tape drive. These parameters could include data compression enabled, variable or fixed block mode, and block size. It also checks that the tape drive media is loaded and write enabled. The application then positions the tape media as necessary before it starts writing customer data on it by issuing Rewind or Space commands. The host application issues a Write FCP_CMND_IU {Command}to the tape drive. When the tape drive is ready to accept the write data, it responds with a FCP_XFER_RDY_IU {Transfer Ready}and the HBA then sends the FCP_DATA_IU {Data}to the tape drive.If FCP Link level errors are detected during this operation, the HBA and the tape drive FC protocol chip performs Link level error recovery that is transparent to the Host application.After checking for errors during the data transfer into the buffer (and possibly data already written on the media), the tape drive returns FCP_RSP_IU {Status}to the HBA and request a confirmation, if supported, of the receipt of the FCP_RSP_IU.If errors were detected by the tape drive, the FCP_RSP_IU contains Check status and Sense bytes identifying the error. It is now up to the host application to do FCP ULP error recovery.If no errors were detected by the tape drive, the FCP_RSP_IU contains Good status. If the HBA supports confirmations, the HBA sends the FCP_CONF_IU {Confirmation}and this Write operation is now complete.The host application can now repeat the above step as many times as necessary to write all the customer data. When all the customer data has been written to the tape drive, the Host application "closes" the tape media by issuing a Write Filemarks command and an Unload command. Notes: Published by ArticulatePresenterwww.articulate.com Notes:You can access the resource page for this accreditation via the Tape Drive Advocate Accreditation Development plan. Notes: Notes: