Product manual

VTrak E-Class Product Manual
370
Each initiator has a unique iSCSI qualified name (IQN). You specify the initiator
by that name when you map a LUN or logical drive to the initiator. Initiators come
in two varieties, software and hardware.
Software
A software initiator uses code to implement iSCSI. The software emulates SCSI
devices for a computer by speaking the iSCSI protocol. Software initiators are
available for most mainstream operating systems, and this type is the most
common mode of deploying iSCSI on computers.
For more information, see your iSCSI driver user documentation.
Hardware
A hardware initiator uses dedicated hardware in combination with software
running on it, to implement iSCSI. A common example is an iSCSI host bus
adapter (HBA) card.
The iSCSI HBA is a 1-gigabit or 10 gigabit Ethernet network Interface card (NIC)
that plugs into a PCI-Express slot. It looks like a SCSI device to the host PC or
server’s operating system.
The iSCSI HBA uses a TCP/IP Offload Engine (TOE) to perform iSCSI and TCP
processing and managing interrupts, leaving the host PC or server’s
microprocessor free to run other applications.
For more information, see your iSCSI HBA user documentation.
Target
The target represents a storage device, in this case the VTrak RAID subsystem.
Each target has a unique iSCSI qualified name (IQN).
VTrak supports a maximum 2048 iSCSI targets. A maximum of 1024 logical
drives can be mapped to a target.
Target options include Digests and CHAPs.
Digests
A header digest adds a 32-bit CRC digest to detect data corruption in the header
portion of each iSCSI packet.
A data digest adds a 32-bit CRC digest to detect data corruption in the data
portion of each iSCSI packet.
If a data packet arrives with an invalid CRC digest, the data packet is rejected.
Header and data digests work best with initiators equipped with a TOE. Refer to
your iSCSI HBA. For more information, see your iSCSI HBA user documentation.