Building an IP storage network with iSCSI storage Technology (Concept chapter)

First, the concept of iSCSI

iSCSI is a standard for data block transmission on Internet protocols, especially Ethernet, which is a new storage technology based on IP storage theory, which combines SCSI interface technology widely used in storage industry with IP network technology, You can build a SAN storage area network on an IP network, simply put, iSCSI is a networked storage technology that runs SCSI protocols on an IP network. iSCSI technology was initially initiated by Cisco and IBM two, and has been strongly supported by a wide range of IP storage technology enthusiasts. The rapid development of these years has grown up.

iSCSI is a great choice for a storage network for small and medium sized enterprises, first of all, in terms of technology implementations, iSCSI is a technical standard based on IP protocol, which allows the network to transmit SCSI commands on TCP/IP protocols and to connect SCSI and TCP/IP protocols. This allows users to build a storage area network over a TCP/IP network, which requires only a few investments, and can facilitate and quickly interactively transfer and manage information and data. But before iSCSI, the only technology to build a storage area network was to use Fibre Channel, which would cost a lot of construction costs, and the average SME was not able to afford it, followed by iSCSI technology to address transmission efficiency, storage capacity, compatibility, openness, security and many other issues, In the use of performance is absolutely not lost to the commercial storage system or fiber storage network.

The advantages of iSCSI are as follows: first of all, iSCSI followed the TCP/IP protocol, while TCP/IP is the most common in the network, the most mature protocol, and the infrastructure of IP network is perfect, at the same time, SCSI technology is disk, tape and other devices widely used storage standards, These two points make iSCSI cost and maintenance costs very low, and second, iSCSI supports generic Ethernet switches rather than special Fibre channel switches, reducing the hassle of heterogeneous networks; Finally, iSCSI is the IP packet Transport storage command, So it can be transmitted across the Internet, with no distance restrictions.

Second, FC sans and IP sans

When iSCSI technology emerged, storage networks built over IP technology came into being, and there were two different implementations of San technology, FC Sans and IP sans. Simply put, fibre-built storage networks are FC Sans, and storage networks built with iSCSI technology are called IP sans.

As the two implementations of Sans, FC sans and IP sans have their pros and cons, and the following are explained separately in several ways:

In the way of data transmission, FC SAN and IP San are implemented by block protocol. This is the same point for them.

On the transmission speed, the current transmission speed is the FC SAN (2GB) the fastest, ISCSI (1Gb) second.

On the transmission distance, the FC San can theoretically reach 100 kilometers, but in fact when the transmission more than 50 kilometers, there will be bottlenecks. iSCSI is theoretically free from the limitations of the IP network, and iSCSI can carry out unlimited data transmission.

In the management and maintenance costs, setting up an FC San network requires a lot of hardware costs, and a specific tool software for operational management, and an IP san is inexpensive to build, because iSCSI is the transfer of data and the allocation of storage resources over an IP network, so long as it is managed and used on existing networks. This will save you a lot of overhead and training costs.

In fact, the IP San also faces some unavoidable problems:

First, ip-based San-based networked storage is not well recognized by users, and secondly, IP SAN storage requires dedicated drivers and devices, but fortunately some traditional fiber adapter vendors have released iSCSI HBA devices, and Inter has also launched a dedicated IP storage adapter, Microsoft, HP, Novell, SUN, AIX, Linux also have iSCSI initiator software and are available to users for free. Finally, on the security side, the IP San has a set of normative security mechanisms, but it has not yet been recognized by users.

These problems and concerns are formidable obstacles to iSCSI development, but the future of iSCSI is bright, and it is believed that in the future storage World, an IP San will definitely have a place.

Iii. the composition of iSCSI

A simple iSCSI system has roughly the following components:

iSCSI Initiator or iSCSI HBAs

ISCSI Target

Ethernet Switch

One or more servers

A complete iSCSI system topology is shown in Figure 1:

Figure 1

In this diagram, iSCSI servers are used to install iSCSI driver, that is, to install iSCSI Initiator,storage Router can be Ethernet switches or routers, iSCSI storage devices can be iSCSI disk arrays, It can also be a PC server with storage capabilities. The following is a detailed description of iSCSI initiator and iSCSI Target: