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• iSCSI is cost effective, allowing use of low cost Ethernet rather than expensive Fibre ARCHITECTURE.
• TRADITIONALLY expensive SCSI controllers and SCSI disks no longer need to be used in each server, reducing overall cost.
• Many iSCSI arrays enable the use of cheaper SATA disks WITHOUT losing hardware RAID functionality.
• The iSCSI storage protocol is endorsed by MICROSOFT, IBM and Cisco, THEREFORE it is an industry standard.
• Administrative/Maintenance costs are reduced.
• Increased utilisation of storage resources.
• Expansion of storage space without downtime.
• Easy server upgrades without the need for data migration.
• Improved data backup/redundancy.

SANs fully exploit high-performance, high connectivity network technologies

SANs expand easily to keep pace with fast growing STORAGE needs

SANs allow any server to access any DATA

SANs help centralize management of storage resources

SANs reduce total cost of ownership (TCO).

ISCSI FUNDAMENTALS

ISCSI is a protocol DEFINED by the Internet Engineering Task Force (IETF) which enables SCSI commands to be encapsulated in TCP/IP traffic, thus allowing access to remote storage over low cost IP networks.

SANs fully exploit high-performance, high connectivity network technologies

SANs expand easily to keep pace with fast growing storage needs

SANs allow any server to access any data

SANs help centralize management of storage resources

SANs reduce total cost of ownership (TCO).

ISCSI fundamentals

ISCSI is a protocol defined by the Internet Engineering Task Force (IETF) which enables SCSI commands to be encapsulated in TCP/IP traffic, thus allowing access to remote storage over low cost IP networks.

NAS or Network Attached Storage

“NAS is used to refer to storage elements that connect to a network and provide file

access services to computer systems. A NAS Storage Element consists of an interface or engine, which implements the file services, and one or more devices, on which data is stored. NAS elements may be attached to any type of network. When attached to SANs, NAS elements may be CONSIDERED to be members of the SAS (SAN Attached Storage) class of storage elements.

A class of systems that provide file services to host computers. A host system that uses network attached storage uses a file system device driver to access data using file access protocols such as NFS or CIFS. NAS systems interpret these commands and perform the internal file and device I/O operations necessary to execute them.

Though the NAS does speed up bulk transfers, it does not offload the LAN like a SAN does. Most storage devices cannot just plug into gigabit Ethernet and be shared - this REQUIRES a SPECIALIZED file server the variety of supported devices is more limited.NAS has various protocols established for such NEEDED features as discovery, access control, and NAME services.

NAS or Network Attached Storage

“NAS is used to refer to storage elements that connect to a network and provide file

access services to computer systems. A NAS Storage Element consists of an interface or engine, which implements the file services, and one or more devices, on which data is stored. NAS elements may be attached to any type of network. When attached to SANs, NAS elements may be considered to be members of the SAS (SAN Attached Storage) class of storage elements.

A class of systems that provide file services to host computers. A host system that uses network attached storage uses a file system device driver to access data using file access protocols such as NFS or CIFS. NAS systems interpret these commands and perform the internal file and device I/O operations necessary to execute them.

Though the NAS does speed up bulk transfers, it does not offload the LAN like a SAN does. Most storage devices cannot just plug into gigabit Ethernet and be shared - this requires a specialized file server the variety of supported devices is more limited.NAS has various protocols established for such needed features as discovery, access control, and name services.

The BURST LENGTH is the number of BYTES that the SCSI initiator sends to the SCSI TARGET in the FCP_DATA SEQUENCE.

The burst length is the number of bytes that the SCSI initiator sends to the SCSI target in the FCP_DATA sequence.

Given multiple connections are ESTABLISHED, individual command/response pair must flow over the same CONNECTION. This connection allegiance ensures that specific read or WRITES commands are fulfilled without any ADDITIONAL overhead of monitoring multiple connections and to see WHETHER a particular request is completed.

Given multiple connections are established, individual command/response pair must flow over the same connection. This connection allegiance ensures that specific read or writes commands are fulfilled without any additional overhead of monitoring multiple connections and to see whether a particular request is completed.

WWPN is the 16 bit character that is assigned to the port, SAN VOLUME controller uses it to uniquely identify the fibre CHANNEL HBA that is installed in the HOST SYSTEM.

WWPN is the 16 bit character that is assigned to the port, SAN volume controller uses it to uniquely identify the fibre channel HBA that is installed in the host system.

Probability that a TRANSMITTED bit will be erroneously received is the measure of number of BITS (ERRONEOUS) at the output of the RECEIVER and DIVIDING by the total number of bits in transmission.

Probability that a transmitted bit will be erroneously received is the measure of number of bits (erroneous) at the output of the receiver and dividing by the total number of bits in transmission.

Jitter refers to any deviation in timing that a bit stream suffers as it traverses the PHYSICAL MEDIUM and the circuitry on-board the end devices. A certain AMOUNT of deviation from the original signaling will occur naturally as serial bit stream propagates over fibre-optic or copper CABLING.

Jitter refers to any deviation in timing that a bit stream suffers as it traverses the physical medium and the circuitry on-board the end devices. A certain amount of deviation from the original signaling will occur naturally as serial bit stream propagates over fibre-optic or copper cabling.

NAS:

• Cables USED in the n/w
• n/w protocols (TCP/IP, IPX) and file sharing protocols (CIFS & NFS)
• Lower TCO
• SUPPORT heterogeneous clients
• Slow

SAN:

• High-speed connectivity such as FC
• Do not use n/w protocols because DATA request are not made over LAN
• Higher TCO
• Requires special s/w to provide access to heterogeneous clients
• Fast

NAS:

SAN:

Latency

Latency

2^24 (24 bit address to the PORT), and the largest POSSIBLE FABRIC will have 239 INTERCONNECTED switches.

2^24 (24 bit address to the port), and the largest possible fabric will have 239 interconnected switches.

A circuit that AUTOMATICALLY removes the storage device from the DATA path (FC device out of FC AL LOOP) when signaling is lost (this signal is called port by-pass signal).

A circuit that automatically removes the storage device from the data path (FC device out of FC AL loop) when signaling is lost (this signal is called port by-pass signal).

• SECURITY and authentication
• CAPACITY, Content and quota management
• Quality of SERVICE

GIGABITS PER SECOND (Gb/ps)

Gigabits per second (Gb/ps)

HBA => HOST BUS adapters are used in STORAGE based traffic while NIC (Network Interface Cards are used in IP based LAN traffic.

HBA => Host bus adapters are used in storage based traffic while NIC (Network Interface Cards are used in IP based LAN traffic.

• MONITORING
• CONFIGURING
• CONTROLLING
• TROUBLESHOOTING
• DIAGNOSING

• STORAGE LEVEL MANAGEMENT
• NETWORK Level Management
• ENTERPRISE Level Management

• HIGH availability CLUSTERS
• High Performance Clusters
• Load BALANCING Clusters.

Port Login: To EXCHANGE service parameters between N_Ports and N_Ports

Process Login: To ESTABLISH the SCSI operating environment between two N_PORTS

Fabric Login: SIMILAR to port login, FLOGI is an extended link service command that SETS up a session between two participants. With FLOGU a session is created between an N_Port or NL_Port and the switch.

Port Login: To exchange service parameters between N_Ports and N_Ports

Process Login: To establish the SCSI operating environment between two N_PORTS

Fabric Login: Similar to port login, FLOGI is an extended link service command that sets up a session between two participants. With FLOGU a session is created between an N_Port or NL_Port and the switch.

EXCHANGE is to establish a relationship between 2 N_PORTs and then these two PORTS transfer data via one or more sequence WITHIN this relationship.

Example: Exchange exist to transfer the command, data and the status of one SCSI task

Exchange is to establish a relationship between 2 N_PORTs and then these two ports transfer data via one or more sequence within this relationship.

Example: Exchange exist to transfer the command, data and the status of one SCSI task

Group of one or more frames that ENCOMPASSES one or more “information units” of a UPPER layer protocol.

Example:It requires

• One sequence to transfer the COMMAND
• One or more sequence to transfer the data
• Once sequence to transfer the status.

Group of one or more frames that encompasses one or more “information units” of a upper layer protocol.

Example:It requires

• DIGITAL LINEAR Tape
• ADVANCED Intelligent Tape
• Linear Tape Open

• REDUNDANCY Functions Relationships Role
• Mirroring Generates 2 ios to 2 STORAGE targets Creates 2 COPIES of data
• Routing Determined by switches independent of SCSI Recreates n/w ROUTE after a failure
• Multipathing Two initiator to one target SELECTS the LUN initiator pair to use

• OFFLINE
• ONLINE
• NEAR LINE

A SPARE DEVICE is available to be INSERTED into the SUBSYSTEM OPERATION without having to remove and replace a device.

A spare device is available to be inserted into the subsystem operation without having to remove and replace a device.

DEVICES are ALLOWED to be REMOVED and inserted into a system WITHOUT turning off the system.

Devices are allowed to be removed and inserted into a system without turning off the system.

Hierarchical STORAGE management - An APPLICATION that attempts to match the PRIORITY of data with the COST of storage.

Hierarchical storage management - An application that attempts to match the priority of data with the cost of storage.

• LINEAR RECORDING
• HELICAL SCAN Recording.

A bad sector is remapped or reallocated to good SPARE block and this INFORMATION is stored in the internal table on the HARD disk drive. The bad blocks are identified during the media test of the HDD as well as during various types of read write operations performed during the I/O tests. APART from the new generation of HDD comes with a technology called BGMS (background media scan) which continuously scans the HDD media for defects and maps them when the drive is IDLE (this is performed after the HDD is attached to the system).

A bad sector is remapped or reallocated to good spare block and this information is stored in the internal table on the hard disk drive. The bad blocks are identified during the media test of the HDD as well as during various types of read write operations performed during the I/O tests. Apart from the new generation of HDD comes with a technology called BGMS (background media scan) which continuously scans the HDD media for defects and maps them when the drive is idle (this is performed after the HDD is attached to the system).

Frame

Frame

It is data distribution scheme that COMPLEMENT s the way operating system REQUEST data. Granularity at which data is stored on ONE DRIVE of the array before SUBSEQUENT data is stored on the next drive of the array. Stripe unit size should be close to the size of the system I/O request.

It is data distribution scheme that complement s the way operating system request data. Granularity at which data is stored on one drive of the array before subsequent data is stored on the next drive of the array. Stripe unit size should be close to the size of the system I/O request.

Fault tolerant technique where, there is more than ONE PHYSICAL path between the CPU in the computer systems and its MAIN storage DEVICES through the BUSES, controllers, switches and other bridge devices connecting them.

Fault tolerant technique where, there is more than one physical path between the CPU in the computer systems and its main storage devices through the buses, controllers, switches and other bridge devices connecting them.

Set of high performance storage disks that can store SEVERAL terabytes of DATA. Single disk ARRAY can support multiple POINTS of connection to the network.

Set of high performance storage disks that can store several terabytes of data. Single disk array can support multiple points of connection to the network.

Probability of unavailability of data stored on the DISK array DUE to single point failure is TOTALLY ELIMINATED.

Probability of unavailability of data stored on the disk array due to single point failure is totally eliminated.

FC Switch USES simple name SERVER (SNS) to maintain the mapping table

FC Switch uses simple name server (SNS) to maintain the mapping table

• LOOP INITIALIZATION
• Loop Monitoring
• Loop ARBITRATION
• OPEN Loop
• Close Loop

• Port Level ZONING
• WWN Level zoning
• DEVICE Level zoning
• PROTOCOL Level zoning
• LUN Level zoning

TWO TYPES of ZONING are:

• SOFTWARE Zoning
• HARDWARE Zoning

Two types of zoning are:

FABRIC MANAGEMENT service that can be USED to create logical subsets of devices within a SAN. This ENABLES portioning of resources for management and access control purpose.

Fabric management service that can be used to create logical subsets of devices within a SAN. This enables portioning of resources for management and access control purpose.

• FC Physical Media
• FC ENCODER and DECODER
• FC Framing and Flow CONTROL
• FC COMMON Services
• FC Upper Level Protocol Mapping

• Point-to-Point
• ARBITRARY LOOP
• SWITCHED FABRIC Loop

LUN: unique number that is assigned to each STORAGE device or PARTITION of the storage that the storage can support.

WWN: 64BIT address that is hard CODED into a fibre channel HBA and this is used to identify INDIVIDUAL port (N_Port or F_Port) in the fabric.

LUN: unique number that is assigned to each storage device or partition of the storage that the storage can support.

WWN: 64bit address that is hard coded into a fibre channel HBA and this is used to identify individual port (N_Port or F_Port) in the fabric.

• FABRIC LOGIN
• SNS
• Fabric ADDRESS Notification
• REGISTERED state change notification
• Broadcast Servers

INTERCONNECTION of FIBRE CHANNEL SWITCHES

Interconnection of Fibre Channel Switches

• DEPLOYMENT DISTANCE (max. of 25 mts)
• Number of devices that can be INTERCONNECTED (16)

7 Classes of service are available in Fibre Channel

Class-1: Dedicated connection between two communicators with acknowledgement of frame delivery.

In class 1 service, a dedicated connection source and destination is established through the fabric for the duration of the transmission. It provides acknowledged service. This class of service ensures that the frames are received by the destination device in the same order in which they are sent, and reserves full bandwidth for the connection between the two devices. It does not provide for a good utilization of the available bandwidth, since it is blocking another possible contender for the same device. Because of this blocking and necessary dedicated connection, class 1 is rarely used.

Class-2: connection less but provides acknowledgement

Class 2 is a connectionless, acknowledged service. Class 2 makes BETTER use of available bandwidth since it allows the fabric to multiplex several messages on a frame-by-frame basis. As frames travel through the fabric they can take different ROUTES, so class 2 service does not guarantee in-order delivery. Class 2 relies on upper layer protocols to take care of frame sequence. The use of acknowledgments reduces available bandwidth, which needs to be considered in large-scale busy networks.

Class-3: connection less and provides no notification of delivery

There is no dedicated connection in class 3 and the received frames are not acknowledged. Class 3 is also called datagram connectionless service. It optimizes the use of fabric resources, but it is now upper layer protocol to ensure that all frames are received in the proper order, and to request to the source device the retransmission of missing frames. Class 3 is a commonly used class of service in Fibre Channel networks.

Class-4: allows fractional bandwidth for virtual circuits

Class 4 is a connection-oriented service like class 1, but the main difference is that it allocates only a fraction of available bandwidth of path through the fabric that connects two N_Ports. Virtual Circuits (VCs) are established between two N_Ports with guaranteed Quality of Service (QoS), including bandwidth and latency. Like class 1, class 4 guarantees in-order delivery frame delivery and provides acknowledgment of delivered frames, but now the fabric is responsible for multiplexing frames of different VCs. Class 4 service is mainly intended for multimedia APPLICATIONS such as video and for applications that allocate an established bandwidth by department within the enterprise. Class 4 was added in the FC-PH-2 standard.

Class -5: Class 5 is called isochronous service, and it is intended for applications that require immediate delivery of the data as it arrives, with no buffering. It is not clearly defined yet. It is not included in the FC-PH documents.

Class-6: Provides multicast, dedicated connection with acknowledgment

Class 6 is a variant of class 1, known as multicast class of service. It provides dedicated connections for a reliable multicast. An N_Port may request a class 6 connection for one or more destinations. A multicast server in the fabric will establish the connections and get acknowledgment from the destination ports, and send it back to the originator. Once a connection is established, it should be retained and guaranteed by the fabric until the initiator ends the connection. Class 6 was designed for applications like audio and video requiring multicast functionality. It appears in the FC-PH-3 standard.

Class-F: used for switch to switch communication in the fabric.

Class F service is defined in the FC-SW and FC-SW-2 standard for use by switches communicating through ISLs. It is a connectionless service with notification of non-delivery between E_Ports used for control, coordination, and configuration of the fabric. Class F is similar to class 2; the main difference is that Class 2 deals with N_Ports sending data frames, while Class F is used by E_ports for control and management of the fabric.

7 Classes of service are available in Fibre Channel

Class-1: Dedicated connection between two communicators with acknowledgement of frame delivery.

In class 1 service, a dedicated connection source and destination is established through the fabric for the duration of the transmission. It provides acknowledged service. This class of service ensures that the frames are received by the destination device in the same order in which they are sent, and reserves full bandwidth for the connection between the two devices. It does not provide for a good utilization of the available bandwidth, since it is blocking another possible contender for the same device. Because of this blocking and necessary dedicated connection, class 1 is rarely used.

Class-2: connection less but provides acknowledgement

Class 2 is a connectionless, acknowledged service. Class 2 makes better use of available bandwidth since it allows the fabric to multiplex several messages on a frame-by-frame basis. As frames travel through the fabric they can take different routes, so class 2 service does not guarantee in-order delivery. Class 2 relies on upper layer protocols to take care of frame sequence. The use of acknowledgments reduces available bandwidth, which needs to be considered in large-scale busy networks.

Class-3: connection less and provides no notification of delivery

There is no dedicated connection in class 3 and the received frames are not acknowledged. Class 3 is also called datagram connectionless service. It optimizes the use of fabric resources, but it is now upper layer protocol to ensure that all frames are received in the proper order, and to request to the source device the retransmission of missing frames. Class 3 is a commonly used class of service in Fibre Channel networks.

Class-4: allows fractional bandwidth for virtual circuits

Class 4 is a connection-oriented service like class 1, but the main difference is that it allocates only a fraction of available bandwidth of path through the fabric that connects two N_Ports. Virtual Circuits (VCs) are established between two N_Ports with guaranteed Quality of Service (QoS), including bandwidth and latency. Like class 1, class 4 guarantees in-order delivery frame delivery and provides acknowledgment of delivered frames, but now the fabric is responsible for multiplexing frames of different VCs. Class 4 service is mainly intended for multimedia applications such as video and for applications that allocate an established bandwidth by department within the enterprise. Class 4 was added in the FC-PH-2 standard.

Class -5: Class 5 is called isochronous service, and it is intended for applications that require immediate delivery of the data as it arrives, with no buffering. It is not clearly defined yet. It is not included in the FC-PH documents.

Class-6: Provides multicast, dedicated connection with acknowledgment

Class 6 is a variant of class 1, known as multicast class of service. It provides dedicated connections for a reliable multicast. An N_Port may request a class 6 connection for one or more destinations. A multicast server in the fabric will establish the connections and get acknowledgment from the destination ports, and send it back to the originator. Once a connection is established, it should be retained and guaranteed by the fabric until the initiator ends the connection. Class 6 was designed for applications like audio and video requiring multicast functionality. It appears in the FC-PH-3 standard.

Class-F: used for switch to switch communication in the fabric.

Class F service is defined in the FC-SW and FC-SW-2 standard for use by switches communicating through ISLs. It is a connectionless service with notification of non-delivery between E_Ports used for control, coordination, and configuration of the fabric. Class F is similar to class 2; the main difference is that Class 2 deals with N_Ports sending data frames, while Class F is used by E_ports for control and management of the fabric.

8b/10b, as the ENCODING TECHNIQUE is able to detect all most all the BIT ERRORS

8b/10b, as the encoding technique is able to detect all most all the bit errors

• Fibre Channel PROTOCOL (FCP)
• Internet SCSI (ISCSI)
• Fibre Channel IP (FCIP)

• JBOD
• RAID

• ETHERNET
• SCSI
• FIBRE CHANNEL