ISCSI initiatorIntroductionA software or hardware device known as an Internet Small Computer System Interface initiator enables data transfer from a host computer to an external iSCSI-based storage array via an Ethernet network adapter over a TCP-based IP network. The ISCSI protocol facilitates communication between input/output (I/O) devices and block storage via a TCP/IP network. With the aid of SCSI commands, the standard offers a means of connecting data storage devices and enabling block-level access to these devices via LANs, WANs, and even the internet. Because it makes it easier to deploy a storage area network over an IP network, ISCSI technology is also referred to as SAN over IP technology. For the protocol to function over large distances, the existing network infrastructure does not need to be significantly upgraded. The ability to run on existing infrastructure sets iSCSI apart from Fibre Channel and other communication technologies. What is target and initiator in iSCSI?iSCSI is an IP-based protocol that facilitates communication between initiators and targets, two different kinds of devices. To allow data transmission to the storage device-also referred to as an iSCSI target-the iSCSI initiator starts the I/O command sequence. Over the TCP/IP network, iSCSI initiators communicate commands to the target. In the event that the initiator is software, the client system's device driver is it. The initiator sends a command over the TCP/IP network, and the iSCSI target receives it and responds to the initiator. Hardware or software could be the target. Hardware iSCSI targets can be gateway devices without any internal or embedded storage, but they are typically storage appliances with embedded storage. To facilitate identification, all iSCSI initiators and targets are assigned unique names. The T11 network address authority, extended unique identifier, and iSCSI qualified name (IQN) are examples of special iSCSI name formats that identify initiators and targets. Every IQN is an ASCII name, which stands for American Standard Code for Information Interchange, and has a byte size of 233. How does iSCSI work with initiators and targets?The client-server model is the foundation of the iSCSI architecture. The initiators are the clients, and they use up storage. The targets are the servers. By communicating with the initiators via commands sent over the TCP/IP network, they share storage with them. Every conversation that takes place between initiators and targets is broken down into messages that are sent as data units for the iSCSI protocol. The fundamental information unit of iSCSI, or PDU, may carry data and communication parameters, control messages, and SCSI commands from the initiator. All communication between initiators and targets occurs via TCP connections that form a session. A session ID is generated, and an initiator is tied to a target (i.e., both can communicate) once the session has begun. To communicate with a target, the initiator must first detect the target node and establish a session. Data is then transferred or shared between the initiator and target via iSCSI commands and responses. Hardware iSCSI vs. software iSCSIA hardware iSCSI initiator is a dedicated host-based network interface card (NIC) that includes resources for iSCSI and TCP/IP processing. The requirement for a TCP/IP offload engine based on NICs has decreased as servers' processing core power has increased. If the card has integrated encryption, a hardware iSCSI initiator might still be helpful for security, data protection, or server booting from a local disk. Usually found in the server operating system (OS), a software iSCSI initiator maps the SCSI I/O command set to TCP/IP so that the iSCSI storage system can use it. It does this by utilizing the host CPU's resources. Software-based iSCSI initiators are much more prevalent than hardware-based iSCSI initiators. How to set up an iSCSI initiator?Numerous operating systems, such as Windows, Red Hat Enterprise Linux (RHEL), and Ubuntu, can be used to configure an iSCSI initiator. WindowsHere are the steps to configure the iSCSI initiator on Windows:
Then, the registry keys need to be changed before accessing the iSCSI initiator via the Run command dialog box, Windows Start menu, file explorer address bar, control panel, and task manager. The iscsicpl.exe command in PowerShell can also be used to open it, but it does require administrator access. Red Hat Enterprise LinuxThe hostname and IP address of the iSCSI target must be known in order to configure an iSCSI initiator on RHEL. The following are the steps to configure the iSCSI initiator on RHEL:
UbuntuIt is crucial to confirm that every network interface is configured correctly before configuring an iSCSI initiator on Ubuntu. Incorrect configurations will cause the open-iscsi package to behave in unexpected ways. To configure the iSCSI initiator on Ubuntu, follow these steps:
Benefits of using iSCSIiSCSI provides numerous benefits to enterprises that use it as part of a SAN. The following are the most common:
What are iSCSI Limitations?Like most technologies, iSCSI has limitations in addition to its many advantages. These are the most typical:
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