Z-Iscsi-Internet Small Computer System Interface-Seminar Report

8/3/2019 Z-Iscsi-Internet Small Computer System Interface-Seminar Report

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iSCSI Seminar Report 03

Dept. of ECE MESCE Kuttippuram-1-

INTRODUCTION

The SCSI protocols widely used to access storage devices. The iSCSI

protocol is a transport for SCSI over TCP/IP. SM-2 defines an architecture

model for SCSI transports, and iSCSI defines such a transport on top of

TCP/IP. Other SCSI transports include SCSI Serial and Fibre Channel Protocol

(FCP). Until recently standard networking hardware (Ethernet) and IP-based

protocols could not provide the necessary high bandwidth and low latency

needed for storage access. With the recent advances in Ethernet technology, it

is now practical from a performance perspective to access storage devices over

an IP network. 1Gb Ethernet is now widely available and is competitive with

current 1 and 2 Gb Fibre Channel technology. 10Gb Ethernet will soon also be

widely available. Similar to FCP, iSCSI allows storage to be accessed over a

storage area network (SAN), allowing shared access to storage. A major

advantage of iSCSI over FCP is that iSCSI can run over standard off-the-shelf

network components, such as Ethernet. Furthermore, iSCSI can exploit IP-

based protocols such as IPSec, for security and Service Location Protocol

(SLP) for discovery. A network that incorporates iSCSI SANs need use only a

single kind of network infrastructure (Ethernet) for both data and storage

traffic, whereas use of FCP requires a separate kind of infrastructure (Fibre

Channel) for storage (Fig.2). IP based SANs using iSCSI can be managed

using existing and familiar IP-based tools such as Simple NetworkManagement Protocol (SNMP) whereas FCI SANs require specialized

management infrastructure. Furthermore, iSCSI-based SANs can extend over

arbitrary distances, just like TCP, and are not subject to distance limitations

that currently limit FCP.


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Fig(1)

Fig.(2) Classic SAN vs iSCSI

In addition to iSCSI, several other protocols have been defined to

transport storage over an IP network. FCIP is used to connect separate islands

of Fibre Channel SANs over an IP network to form a single unified SAN. iFCP

is a gateway-to-gateway protocol for the implementation of Fibre Channel

fabric functionality on a network in which TCP/IP switching and routing

elements replace Fibre Channel components. Whereas, FCIP and iFCP are

used to allow the connection of existing Fibre Channel infrastructures to each

other and to IP network. iSCSI enables the creation of SANs complete

independent of Fibre Channel.


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FACTORS ENABLING IP STORAGE

SAN deployments have been driven by an insatiable demand for storage

and the user benefits delivered by networked storage. These benefits include

efficient storage. These benefits include efficient storage utilization through

storage consolidation, the ability to manage more storage capacity, rapid

deployment of new storage, higher availability, and faster backup and restore

operations.

With the recent development of the iSCSI protocol and silicon-based

TCP/IP offload engines, SANs based TCP/IP networks are now possible. The

IP networking infrastructure includes multi-gigabit networks, sophisticated

bandwidth allocation and network management tools, and the ubiquitous reach

of IP and Ethernet. These factors together enable new IP Storage solutions,

using iSCSI protocol.

Fig.3 Factors enabling iSCSI storage


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LEVERAGING THE BEST FROM STORAGE AND

NETWORKING

iSCSI builds on the two most widely used protocols from the storage and

the networking worlds. From the storage side, the iSCSI used the SCSI

command set, the core storage commands used throughout all storage

configurations.

On the networking side, iSCSI uses IP and Ethernet, which are the basis

for the most corporate networks, and are increasingly being used for

metropolitan and wide area networking as well. With almost eighty years of

research, development and integration, IP networks provide the almost in

manageability, interoperability and cost-effectiveness.

Fig.4 Leveraging SCSI and IP for Storage Fig.5 iSCSI Protocol

Network Stack

Fig.4 shows how SCSI is mapped to TCP/IP through the

discs layer, freeing SCSI from its parallel bus structure.


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Fig.5 shows a simplified version of a protocol stack

including iSCSI. Use of the standard SCSI command set facilities

interoperability with existing operating system and applications that lay above

that layer. Additionally, use of a standard TCP/IP network provides universal

reach to the global IP infrastructure.


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ADVANTAGES OF IP STORAGE

*Familiar network technology and management

Reduces training and staff cost

*Proven transport infrastructure

Increases reliability

*Transition from 1Gigabit Ethernet to 10 Gigabit Ethernet and beyond

Protects investment with simplified performance upgrades

*Scalability over long distances

Enables remote data replication and disaster recovery

*Brings Ethernet economics to storage

Enables lower total cost of ownership


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ELEMENTS OF IP STORAGE NETWORKING

IP Storage Networking refers to computer systems and storage

elements that are connected via IP. It also refers to the IP infrastructure

transporting storage traffic among these targets. Fig.6 shows the various

elements of an IP storage network.

The first element, Device I/O, refers to computer systems and

storage resources that have native IP interfaces. These could include servers,

disk arrays or tape libraries with an iSCSI adapter or iSCSI controller. The

interfaces typically are Ethernet and include protocol processing, such as

TCP/IP offload engines to reduce processing loads on the host devices.

The second element of an iSCSI storage area network is the fabric of

switches. The advantage of an IP based fabric is that users can create a SAN

using standard Ethernet switches and routers to transport data over the SAN

fabric. The fabric also may include storage routers and switches that have a

combination of iSCSI interfaces and other storage interfaces such as SCSI or

Fiber Channel. Storage switches and routers provide multi-protocol

connectivity not available in conventional IP and Ethernet switches. They also

provide storage specific functionality, such as peer-to-peer copy commands.

The third element of IP storage networking is the SAN

interconnection. Since iSCSI is a native IP based protocol, SAN

interconnection does not require storage-specific functionality and can use a

shared or dedicated IP/Ethernet network.


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Fig.6 Segments of Storage Networking


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iSCSI DEFINED

Internet SCSI (iSCSI) is a draft standard protocol for encapsulating SCSI

command into TCP/IP packets and enabling I/O block data transport over IP

networks. iSCSI can be used to build IP-based SANs. The simple, yet powerful

technology can help provide high-speed, low-cost, long-distance storage

solution for Web sites, service providers, enterprises and other organizations.

An iSCSI HBA, or storage NIC, connects storage resources over Ethernet. As

a result, core transport layers can be managed using existing network

management applications. High-level management activities of the iSCSI

protocol such as permissions, device information and configuration can

easily be layered over or built into these applications. For this reason, the

deployment of interoperable, robust enterprise management solutions for

iSCSI devices is expected to occur quickly.

First-generation iSCSI HBA performance is expected to be well suited

for the workgroup or departmental storage requirements of medium- and large-

sized businesses. The expected availability of TCP/IP Offload Engines in 2002

will significantly improve the performance of iSCSI products. Performance

comparable to Fibre Channel is expected when vendors begin shipping 10

Gigabit Ethernet iSCSI products in 2003.


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Fig 7. Layered View

BENEFITS OF ISCSI

By combining SCSI, Ethernet and TCP/IP, Gigabit iSCSI delivers these

key advantages: Builds on stable and familiar standards many IT staffs are familiar with

the technologies

Creates a SAN with a reduced TCOinstallation and maintenance costs arelow since the TCP/IP suite reduces the need for hiring specialized

personnel

Provides a high degree of interoperabilityreduces disparate networks andcabling, and uses regular Ethernet switches instead of special Fibre

Channel switches

Ethernet transmissions can travel over the Global IP Network and thereforehave no practical distance limitations

Scales to 10 Gigabit comparable toOC-192 SONET (SynchronousOptical Network) rates in Metropolitan Area Networks (MANs) and Wide

Area Networks (WANs)


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WHO CAN USE IT

iSCSI SANs are most suitable for organizations with a need for

streaming data and/or large amounts of data to store and transmit over the

network.

This includes:

Internet Service Providers (ISPs)

Storage Service Providers (SSPs) Organizations that need remote data replication and disaster recovery. For

example, a high-technology company in San Jose remains susceptible to

disaster if it uses a Fibre Channel SAN. Original and backup data copies

could be lost in the same earthquake due to distance limitations.

Geographically distributed organizations that require access to the samedata on a real-time basis. For example, work team members who need the

latest project data without waiting 24 hours for traditional

replication/backup/ reconciliation procedures.

Businesses and institutions with limited IT resources, infrastructure andbudget. These organizations should look for iSCSI equipment those

functions over standard Gigabit Ethernet Cat-5 copper cabling already in

place in most buildings today.


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ISCSI FEATURES

TCP

TCP was chosen as the transport for iSCSI. TCP has many features that

are utilized by iSCSI :

1. TCP provides reliable in-order delivery of data.2. TCP provides automatic retransmission of data that was not

acknowledged.

3. TCP is a friendly network citizen in that it provides the necessary flowcontrol and congestion control to avoid overloading a congested

network.

4. TCP works over a wide variety o physical media and interconnecttopologies.

While other protocols such as SCTP also provide many of these

features, TCP has the advantage of having been deployed for decade and is

therefore better understood and more widely available.

SESSIONS

SCSI commands are typically issued by a storage initiator (client) to a

storage target (server). The relationship between SCSI entities is referred as

nexus. The iSCSI entity corresponding to an I_T_NEXUS (initiator-target

nexus) is an iSCSI session. An iSCSI session is a collection of TCP

connections between an iSCSI initiator and an iSCSI target used to pass SCSI

commands are data between the initiator and the target.


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Even though a single TCP connection is sufficient to establish

communication between an initiator and a target, it is often advantageous use

multiple connections:

1. It is often not possible to achieve the maximum bandwidth of theunderlying physical interconnect using only a single TCP connection.

2. When working on a multiprocessor machine, it may be advantageous toallow separate threads running on the different processors to

simultaneously utilize different TCP connections.

3. If there are more than one physical interconnect between the initiatorand the target, spreading multiple TCP connections over all the possible

physical interconnects can aggregate their bandwidth.

ISCSI PROTOCOL DATA UNITS

iSCSI defines its own packets, referred to as iSCSI protocol data

units (PDUs). iSCSI PDUs consist of a header and possible data, where the

data length is specified within the iSCSI PDU header. An iSCSI PDU is sent as

the contents of one or more TCP packets.

The most commonly used iSCSI PDU types are :

(i) SCSI Command/Response.(ii)

Data In/Out

(iii) Ready to Transfer (R2T).(iv) Login Request/Response.

The SCSI Command PDU is used to transfer a SCSI command

from the initiator to the target. If the SCSI commands requests to read data

from the target, the target will send the data to the initiator in one or more Data

In PDUs. If the SCSI command requests to write data to the target, the initiator


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will send data to the target in one or more Data Out PDUs. The target may

specify to the initiator which part of the data to send by sending to the initiator

an R2T PDU. Upon completion of the entire data transfer, the target sends a

SCSI Response PDU to the initiator indication either successful completion of

the command or any error condition detected. For each SCSI Command PDU

there is a corresponding single SCSI Command PDU there is a corresponding

single SCSI Response PDU, but possibly multiple (or no) Data PDUs. SCSI

Data and Response PDUs must be sent over the same TCP connection on

which their corresponding SCSI Command PDU was issued.

LOGIN

Immediately upon establishing a TCP connection between an

iSCSI initiator and iSCSI target, a login procedure must be performed. The

initiator sends a Login Request PDU to the target. The initiator and target may

authenticate each other and may negotiate operational parameters. A default

authentication method, Challenge-Handshake Authentication Protocol

(CHAP), must be supported by all compliant iSCSI implementations. Some of

the operational parameters that may be negotiated are the maximum number of

connections to be used in the session, the amount of unsolicited data that may

be sent by the initiator, the level of error recovery supported, and whether or

not digests will be used for error detection. After both sides are satisfied with

the authentication and the setting of the operational settings, the target sends aLogin Responds PDU with an indication that the login procedure has

completed. Only then may the connection be used to pass SCSI commands and

data.


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NAMING

Borrowing from other Internet protocols, iSCSI use an URL-like

scheme to name targets. ISCSI names are meant to be global, similar to World

Wide Names used by Fibre Channel. An iSCSI entity might have its IP address

changed while retaining its name. An iSCSI entity is therefore identified by its

name and not its address. This allows for easier handling of iSCSI names by

proxies, gateways, network address translation boxes, firewalls, and so on.

iSCSI names should be unique worldwide. Typical iSCSI names might look

like this:

Iqn.2001-04.com.acme:storage.disk2.sys1.xyz

DISCOVERY

When using storage devices over a network, one has to deal with

the ability of an initiator to discover the devices it may use. One approach is

for an administrator to statically configure the initiator, providing the initiator

with a list of names and addresses of the iSCSI devices to which the initiator

may connect. If additional iSCSI devices were later added to the network, the

statically configured initiator would not be able to access the new devices

without being reconfigured. An alternative more dynamic method is to use

SLP, which already exists in the IP family of protocols. iSCSI targets can beadded to the network, and the topology can change over time, but initiators can

easily find new targets without having to be reconfigured. A similar

mechanism is provided by the recently defined iSNS protocol.

An additional discovery mechanism, Send Targets, is provided in

the iSCSI protocol itself, especially useful for gateway devices. In this method,

an initiator is statically configured to connect to specific iSCSI gateway


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devices. The initiator establishes a discovery session with the iSCSI gateway

device then responds with a list of attached iSCSI targets that are available to

the initiator. The initiator may then proceed to connect to the specified iSCSI

target devices.

DATA INTEGRITY

TCP has a checksum facility to help detect errors that occur

during transmission. While the probability of the TCP checksum failing to

detect an error is quite small, it is not good enough for some storage

environments. The TCP checksum also does not provide protection for

corruptions that occur while a message is in the memory of some router. iSCSI

therefore defines its own cyclic redundancy check (CRC) checksum to ensure

end-to-end integrity of its packet headers and data. Initiators and targets may

negotiate whether or not to use this CRC checksum.

SECURITY

When storage devices were directly attached to host machines, the

data on the storage devices was considered secure by its being inaccessible to

the outside world. With iSCSI attached storage devices, this is no longer the

case. A serious security problem may arise if sensitive storage data is accessed

over a general data network. One possible solution is to use a physicallyseparate network for the storage data, similar to what is done with Fibre

Channel (Fig.2. This solution requires a second physical IP network which is

still cheaper than having a second physical Fibre Channel network.

Alternatively, a single physical IP network can be used to get with encryption

of the storage data. Encryption of data on an IP network can be provided with

IPSec. iSCSI simply uses the existing IP-faulty security protocol to protect

sensitive storage data from possible security attacks such as spoofing.


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ANTICIPATED USE OF iSCSI

Some of the design decisions of iSCSI were strongly influenced

by the perception of how iSCSI would eventually be used. ISCSI was designed

to allow efficient hardware and software implementations to access I/O

devices attached over any IP network. iSCSI was designed for a wide variety

of environments and applications including local and remote storage access,

local and remote mirroring, local and remote backup/restore. It was assumed

that TCP/IP acceleration adapters and even iSCSI host bus adapters (HBAs)

would become prevalent, and would be strongly desirable to defend he

protocol to allow high-performance adapter implementations Mechanisms

were therefore included to overcome various anticipated problems, such as

maintaining high bandwidth frequently dropped packets. Care was taken to not

limit the application of iSCSI to disks; mechanisms were provided for various

types of SCSI devices, especially tapes, for which it is inconvenient and

perhaps prohibitive to cancel a restart commands.

DIRECT DATA PLACEMENT

In typical TCP implementations, data that arrive on a TCP

connection is first copied into temporary buffers. The TCP driver then

examines the connection identification information (source and destinationaddress and port numbers) determine the intended receiver of the data. The

data is then copied into the receivers buffer. For SCSI data, there might be

many pending SCSI commands at any given instant, and the received data

typically mist be copied into the specific buffer provided by the SCSI layer for

the particular command. This entire procedure might require the receiving host

to copy the data a number of times before the data ends up in the final

destination buffer. Such copies require significant amount of CPU and memory


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buffer usage that would adversely affect the system performance. It is

therefore most desirable to the able to place the data in its final destination

with a minimum number of copies.

iSCSI Data PDU headers contain sufficient information allow an

iSCSI adapter (HBA) perform direct data placement. The information provided

in an iSCSI Data PDU header include a transfer tag to identify the SCSI

command and its corresponding buffer, a byte offset relative the beginning of

the corresponding buffer, and the data length parameter indicating the number

of bytes being transferred in the current data packet. This information is

sufficient to enable direct placement of the arriving data into pre registered

SCSI-provided buffers. An iSCSI adapter then performs both TCP and iSCSI

processing on the adapter will have sufficient information in the TCP and

iSCSI headers to place arriving iSCSI data directly into the appropriate SCSI

buffers without having to copy the data into additional temporary buffers on

the host machine.

RECOVERY

The iSCSI protocol defines several levels of recovery to provide

resilience in the face of a wide range of possible errors and failures. iSCSI

handling and recovery is expected a rare occurrence, and may involve a

significant amount of overhead. It is anticipated that most computingenvironments will not need all the levels of recovery defined in the iSCSI

specification.

The most basic recovery class is session failure recovery. All

iSCSI specification complaint implementations must implement session failure

recovery. Session recovery involves the closing of all of the sessions TCP

connections aborting all outstanding SCSI commands on that session,


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terminating all such aborted SCSI commands with an appropriate SCSI service

response at the initiator and the restarting a new set of TCP connections for the

particular session. Implementations may perform session failure recovery for

any iSCSI error detected.

A less drastic kind of recovery implementations may perform its

digest failure recovery. If a CRC checksum error is detected on iSCSI data, the

data packet must be discarded. Instead of performing session recovery,

implementations may use the digest failure recovery mechanism to ask the

connecting peer to resent only the missing data. Similarly, if a sequence

reception timeout occurs, a similar mechanism can be used to ask the

connecting peer to resent the missing commands, responses or other number

packets that are expected.

If a CRC checksum error is detected on an iSCSI packet header,

the packet must be discarded since it was corrupted. As a result,

synchronization between the initiator and target may be lost. The iSCSI

protocol allows for a new TCP connection to be established within the session,

and defines mechanisms for the initiator and target to synchronize with one

another to continue to smoothly interact. A new TCP connection may be

designated to take over from an old TCP connection that seems to have

become defective. This level of recovery is called connection recovery.

Processing of commands that were started on the defective TCP connection

can be continued on the new TCP connection.


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UNDERSTANDING END SYSTEMS

An iSCSI environment can leverage existing IP networks; a

significant portion of the overall solution involves iSCSI end systems. Fig.8

outlines the significant functions of traditional IP Network Interface Cards,

traditional Storage Adapters, and new IP Storage Adapters.

Fig.8 Network Interface Cards and Host Bus Adapters

Network Interface Cards (NICs)

Traditional NICs (Ethernet adapters in servers and PCs) are

designed to transfer packetized file level data among PCs, servers and storage

devices, such as NAS appliances. However, NICs do not traditionally transfer

block level data, which is handled by a storage host bus adapter, such as Fibre

Channel or parallel SCSI. In order for a NIC to process block level data the

data needs to be placed into a TCP/IP packet before being send over the IP

network. Through the use of iSCSI drivers on the host or server, a NIC can

transmit packets of block level data over an IP network. When using an NIC,

the server handles the packet creation of block level data and performs all of


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the TCP/IP processing. This is extremely CPU intensive and lowers the overall

server performance. The TCP/IP processing performance bottleneck has been

the driving force behind the development of TCP/IP offload engines (TOE) on

adapter cards. A TOE removes TCP/IP processing from the host CPU and

completes TCP/IP processing and packet creation on the HBA. Thus a TCP/IP

offload storage NIC operates more like a storage HBA rather than a standard

NIC.

Storage Host Bus Adapters (HBAs)

Unlike NICs, Storage HBAs are designed to transmit block level

data to and from storage applications. A reference to the entire block is

transferred from the application to the adapter, bypassing the need to bread the

bloke into smaller frames; a process that takes place through a set of

specialized chips that enable the HBA to relieve the computer resources of the

CPU for this process. When it completes the task, the HBA forwards the

frames.

ISCSI ADAPTERS

iSCSI Adapters combine the functions of NICs with the function

of storage HBA. These adapters take the data in block form, handle the

segmentation and processing on the adapter card with TCP/IP processing

engines, and then send the IP packets across an IP network. The

implementation of these functions enables users to create an IP based SAN

without lowering the performance of the server. In advance of the introduction

of iSCSI adapters, some vendors released software versions of these adapters.

These software-enabled adapters accept block level data from applications, but

still require CPU cycles for the TCP/IP processing. The advantage of such

adapters is that they can work on existing Ethernet NICs. The main

disadvantage is that they require heavy CPU utilization for TCP/IP processing.


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DEPLOYMENT SCENARIOS FOR ISCSI

BUILDING NEW NATIVE ISCSI STORAGE NETWORKS

DATA CENTER APPROACH

An iSCSI SAN is a perfect choice for a user interested in moving

to networked storage. Using the same block level SCSI commands as direct

attach storage, iSCSI provides compatibility with user applications such as file

systems, databases, and web serving. Similarly, since iSCSI runs on ubiquitous

and familiar IP networks, there is no need to learn a new networking

infrastructure to realize SAN benefits. To build an iSCSI storage network in a

data center, iSCSI host bus adapters can be used in servers, along with iSCSI

storage devices and a combination of IP and Ethernet switches. IP Storage

switches and routers can be used if required. Fig.8 shows aprimary data center

iSCSI storage network connecting to remote sites.

Fig.9 Data Center iSCSI Storage Networks Offer Seamless MAN/WAN Access


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EXPANDING ISCSI STORAGE NETWORKS TO METRO AND WIDE

AREA NETWORKS

The rapid adoption and expansion of IP data on the Internet has proves

the viability of using IP across long distance wide area networks. Although it

is expected that initial deployments of iSCSI will use private networks, the use

of IPs security infrastructure (such as IPSes and SSL to provide authentication

and privacy) it will be possible to use public networks for wide area iSCSI

storage traffic as well.

APPLICATIONS FOR NATIVE ISCSI STORAGE NETWORKS

With native iSCSI storage networks customers can benefit from the

following applications in the data center:

(1)Server and storage consolidation

With a networked storage infrastructure, customers can link

multiple storage devices to multiple servers allowing for better resource

utilization, ease of storage management and simpler expansion of the storage

infrastructure.

(2)Accelerated Backup OperationsBackup operations previously restricted to operating across

traditional IP LANs at the file level can now operate across IP Storage

networks at the block level. This shift facilitates faster backup times, and

provides customers the flexibility to use shared or dedicated IP networks for

storage operations.


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(3)Seamless Remote Site Access and Storage Outsourcing

With the storage network based on IP, customers can easilyenable remote access to secondary sites across metropolitan or wide area IP

networks. The remote sites can be used for off-state backup, clustering or

mirroring/replication. Additionally, customers can choose to link to storage

service providers for storage outsourcing applications such as storage-on-

demand


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LINKING SANs WITH iSCSI

The iSCSI protocol is ideal for linking SANs over MAN and

WAN environments wince it uses TCP/IP as the transport. This includes

extending native iSCSI SANs and Fibre Channel SANs across a wide area

network. iSCSI SANs can be connected over a wide area network with

standard Ethernet equipment. When connecting to Fiber Channel SANs, an IP

Storage Switch is needed to convert the FC protocol to iSCSI.

IP Storage routers can bridge FC to iSCSI, while IP storage

switches bridge FC to iSCSI and provide added switching functionality. That

functionality, when provided in an IP Storage switch, allows users to perform

FC-to-FC switching, FC-to-iSCSI switching, or FC-to-Gigabit Ethernet

switching and Gigabit Ethernet to Gigabit Ethernet switching. Both IP storage

routers and switches allow users to extend the reach of the FC SAN and bridge

FC SANs to iSCSI SANs. Fig.10 shows a sample configuration based on IP

storage routers and switches.

Fig.10 Linking iSCSI to Fibre Channel


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Fig.(11)


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APPLICATIONS FOR LINKING ISCSI TO FIBRE

CHANNEL

IP Access to Storage/Storage Consolidation

Using iSCSI Adapters in servers, customers can now provide

access to FC storage resources across an IP network. This greatly expands

storage access flexibility, allowing customers to consolidate FC storage

without limiting access to servers. Database information, for example, can be

directly accessed from servers across an IP network.

Remote Backup for Enterprise Customers

With the ability to use IP networks, the combination of iSCSI and

IP Storage routers or switches enables remote backup for enterprise customers.

Remote sites can operate independently, yet still benefit from enterprise

storage resources for iSCSI server to FC storage backup and recovery. This

application allows data center managers to centralize corporate data resources

in one location while providing sophisticated enterprise storage management to

several remote customers at different sites.


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DEPLOYMENT EXAMPLES

Network Storage Services via iSCSI

Two iSCSI HBAs can be used in conjunction with standard Ethernet

NICs through a Gigabit-capable switch connected to an iSCSI-capable RAID

Array (Figure12). This configuration is appropriate as either the next step in

transitioning to an iSCSI-exclusive SAN or as an initial iSCSI SAN

configuration.

Fig.12 Network Storage Services via iSCSI

Multiple Cards to Single iSCSI Router

Multiple HBAs in separate servers can be used in conjunction

with a Gigabit capable switch connected to an iSCSI capable router with Fibre

Channel ports. This is then connected directly to a native Fibre Channel RAID

Array (Figure 13). This configuration is appropriate as the next step in

transitioning to an iSCSI front-end SAN with Fibre Channel storage devices.


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Fig.13 Multiple Cards to Single iSCSI Router

iSCSI HBA and Fibre Channel Tape Backup

An iSCSI HBA can be used in conjunction with a Gigabit-capable

switch connected to an iSCSI-capable router with Fibre Channel ports

connected to a Fibre Channel tape drive (Figure 14). This configuration can be

used as a means to perform backup and recovery using existing Ethernet

infrastructure.

Fig.14 iSCSI HBA and Fibre Channel Backup


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CONCLUSION

The iSCSI protocol enables access to storage devices over an IP

network. One of the main objectives in defining the iSCSI protocol was to

make use of existing IP infrastructure whenever possible. Thus, TCP is used as

the underlying transport, IPSec is exploited to provide network security, SLP

can be used to provide discovery, and so on. Since iSCSI runs over standard

off-the-shelf network compoens, the cost of setin up an iSCSI SAN is

significantly lower than that of a Fibre Channel SAN. This will make iSCSI

more affordable and manageable than Fibre Channel, and enable it to become

the protocol of choice for SANs. iSCSI will expand the market for networked

storage by giving IT managers another alternative to direct attached storage

that delivers the advantages of networked storage. IP storage networks take

advantage of IP networking knowledge in IT departments and use existing

network management and tools for LANs, MANs and WANs today. Riding the

IP wave of technology develoment and enhancements like the introduction of

10 Gigabit Ethernet, iSCSI provides a logical unified infrastructure

development path for corporations and service providers alike.


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REFERENCES

Features of iSCSI Protocol, Kalman. Z. Meth and Julian Satran, IBMHaifa Research Lab, IEEE Communication MagazineAugust 2003.

Performance Study of iSCSI-Based Storage Subsystems, Yingping Luand David. H. C. Du, University of Minnesota, IEEE Communication

MagazineAugust 2003.


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ACKNOWLEDGEMENT

I extend my sincere thanks to Prof. P.V.Abdul Hameed, Head of

the Department for providing me with the guidance and facilities for the

Seminar.

I express my sincere gratitude to Seminar coordinator Mr. Manoj K,Staff in charge, for his cooperation and guidance for preparing and presenting

this seminar.

I also extend my sincere thanks to all other faculty members of

Electronics and Communication Department and my friends for their support

and encouragement.

Sreeraj. K.P


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CONTENTS

INTRODUCTION ELEMENTS OF IP STORAGE FACTORS ENABLING IP STORAGE LEVERAGING THE BEST FROM STORAGE AND NETWORKING ADVANTAGES OF IP STORAGE ELEMENTS OF IP STORAGE NETWORKING ISCSI DEFINED BEBEFITS OF ISCSI WHO CAN USE IT ISCSI FEATURES

TCP

SESSIONS

ISCSI PROTOCOL DATA UNITS

LOGIN

NAMING

DISCOVERY

DATA INTEGRITY

SECURITY

ANTICIPATED USE OF ISCSI

DIRECT DATA PLACEMENT

RECOVERY

UNDERSTANDING END SYSTEMS DEPLOYMENT SCENARIOS FOR ISCSI APPLICATIONS FOR LINKING ISCSI TO FIBRE CHANNEL DEPLOYMENT EXAMPLES CONCLUSION REFERENCES


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ABSTRACT

In a world where Internet Protocol (IP) dominates local and

wide area networks, the data storage requirements grow unabated; it seems

inevitable that these two forces converge. The Internet Small Computer

Systems Interface (iSCSI) protocol unites storage and IP networking. iSCSI

enables the transport of block-level storage traffic over IP networks. It builds

on two widely used technologies - SCSI commands for storage traffic over IP

networks. It builds on two widely used technologies - SCSI commands for

storage and IP protocols for networking. iSCSI is an end-to-end protocol for

transporting storage I/O block data over an IP network. The protocol is used on

servers (initiators), storage devices (targets), and protocol transfer gateway

devices. iSCSI uses standard Ethernet switches and routers to move the data

from server to storage. It also enables IP and Ethernet infrastructure to be used

for expanding access to SAN storage and extending SAN storage and

extending SAN connectivity across any distance. This paper presents general

overview of iSCSI, outlining its introduction, details of the protocol, its

features, user benefits, and several typical deployment scenarios and

applications.

Z-Iscsi-Internet Small Computer System Interface-Seminar Report

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Transcript of Z-Iscsi-Internet Small Computer System Interface-Seminar Report