A hardware initiator mitigates the overhead of iSCSI and TCP processing and Ethernet interrupts, and therefore may improve the performance of servers that use iSCSI.Īn iSCSI host bus adapter (more commonly, HBA) implements a hardware initiator.
#INITIATER DEFINITION SOFTWARE#
Software initiators are available for most popular operating systems and are the most common method of deploying iSCSI.Ī hardware initiator uses dedicated hardware, typically in combination with firmware running on that hardware, to implement iSCSI.
#INITIATER DEFINITION DRIVER#
Typically, this happens in a kernel-resident device driver that uses the existing network card (NIC) and network stack to emulate SCSI devices for a computer by speaking the iSCSI protocol.
#INITIATER DEFINITION CODE#
An initiator falls into two broad types:Ī software initiator uses code to implement iSCSI. An initiator typically serves the same purpose to a computer as a SCSI bus adapter would, except that, instead of physically cabling SCSI devices (like hard drives and tape changers), an iSCSI initiator sends SCSI commands over an IP network. Initiator Īn initiator functions as an iSCSI client. In particular, iSCSI SANs allow entire disk arrays to be migrated across a WAN with minimal configuration changes, in effect making storage "routable" in the same manner as network traffic. Disaster recovery Organizations mirror storage resources from one data center to a remote data center, which can serve as a hot / standby in the event of a prolonged outage. In a SAN environment, a server can be allocated a new disk volume without any changes to hardware or cabling. Storage consolidation Organizations move disparate storage resources from servers around their network to central locations, often in data centers this allows for more efficiency in the allocation of storage, as the storage itself is no longer tied to a particular server. iSCSI SANs often have one of two objectives: However, the performance of an iSCSI SAN deployment can be severely degraded if not operated on a dedicated network or subnet (LAN or VLAN), due to competition for a fixed amount of bandwidth.Īlthough iSCSI can communicate with arbitrary types of SCSI devices, system administrators almost always use it to allow servers (such as database servers) to access disk volumes on storage arrays. As a result, iSCSI is often seen as a low-cost alternative to Fibre Channel, which requires dedicated infrastructure except in its FCoE (Fibre Channel over Ethernet) form. Unlike some SAN protocols, iSCSI requires no dedicated cabling it can be run over existing IP infrastructure. By doing this, iSCSI takes a popular high-performance local storage bus and emulates it over a wide range of networks, creating a storage area network (SAN). In essence, iSCSI allows two hosts to negotiate and then exchange SCSI commands using Internet Protocol (IP) networks. iSCSI was pioneered by IBM and Cisco in 1998 and submitted as a draft standard in March 2000. It mainly competes with Fibre Channel, but unlike traditional Fibre Channel which usually requires dedicated cabling, iSCSI can be run over long distances using existing network infrastructure. It is a storage area network (SAN) protocol, allowing organizations to consolidate storage into storage arrays while providing clients (such as database and web servers) with the illusion of locally attached SCSI disks. The protocol allows clients (called initiators) to send SCSI commands ( CDBs) to storage devices ( targets) on remote servers. It can be used to transmit data over local area networks (LANs), wide area networks (WANs), or the Internet and can enable location-independent data storage and retrieval. iSCSI facilitates data transfers over intranets and to manage storage over long distances. iSCSI provides block-level access to storage devices by carrying SCSI commands over a TCP/IP network. Internet Small Computer Systems Interface or iSCSI ( / ˈ aɪ s k ʌ z i/ ( listen) EYE-skuz-ee) is an Internet Protocol-based storage networking standard for linking data storage facilities. ( Learn how and when to remove this template message)
( February 2019) ( Learn how and when to remove this template message) There might be a discussion about this on the talk page. This article may be confusing or unclear to readers.
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