iSCSI SAN components

iSCSI (Internet Small Computer System Interface) encapsulates SCSI control and data in TCP/IP packets, allowing access to storage devices over the existing network infrastructure. An iSCSI SAN usually consists of the following components:

  • iSCSI storage system – a physical storage system on the network.
  • LUN (Logical Unit Number) – a number used to identify a device addressed by the iSCSI protocol.
  • iSCSI target – a logical target-side device that hosts iSCSI LUNs and masks to specific iSCSI initiators. An iSCSI target receives SCSI commands from the iSCSI initiator over the IP network.
  • iSCSI initiator – a logical host-side device that transmits SCSI commands to iSCSI target over the IP network. An iSCSI initiator resides on the ESXi host.
  • iSCSI Network Portal – IP addresses used by an iSCSI initiator or iSCSI target.
  • iSCSI Qualified Name (IQN) – the unique identifier for an iSCSI initiator, target, or LUN.
  • iSCSI Naming Service (iSNS) – a protocol that allows automated discovery, management and configuration of iSCSI devices on an IP network. Rarely used today.

The following picture gives you an overview of iSCSI components (source: VMware):

iscsi components

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