Chelsio Communications Terminator 6, Installation And User Manual, Page: 151 / 432

Chapter X. iSCSI PDU Offload Target
Chelsio Unified Wire for Linux 151
T420-CR
T440-CR
T422-CR
T404-BT
T420-BCH
T440-LP-CR
T420-BT
T420-LL-CR
T420-CX
Adapter Requirements
The Chelsio iSCSI PDU Offload Target software can be used with or without hardware protocol
offload technology. There are two modes of operation using the iSCSI PDU Offload Target
software on Ethernet-based adapters:
Regular NIC
– The software can be used in non-offloaded (regular NIC) mode. Please note
however that this is the least optimal mode of operating the software in terms of performance.
iSCSI HW Acceleration
– In addition to offloading the TCP/IP protocols in hardware (TOE),
this mode also takes advantage of Chelsio’s ASIC capability of hardware assisted iSCSI data
and header digest calculations as well as using the direct data placement (DDP) feature.
Storage Requirements
When using the Chelsio iSCSI target, a minimum of one hardware storage device is required.
This device can be any of the device types that are supported (block, virtual block, RAM disk).
Multiple storage devices are allowed by configuring the devices to one target or the devices to
multiple targets. The software allows multiple targets to share the same device but use caution
when doing this.
Chelsio’s implementation of the target iSCSI stack has flexibility to accommodate a large range
of configurations. For quick testing, using a RAM Disk as the block storage device works nicely.
For deployment in a production environment a more sophisticated system would be needed. That
typically consists of a system with one or more storage controllers with multiple disk drives
attached running software or hardware based RAID.
1.3. Software Requirements
chiscsi_base.ko
is iSCSI non-offload target mode driver and
chiscsi_t4.ko
is iSCSI PDU
offload target mode driver.
cxgb4, toecore, t4_tom and chiscsi_base modules are required by
chiscsi_t4.ko
module to
work in offloaded mode. Whereas in iscsi non-offloaded target (NIC) mode, only cxgb4 is needed
by chiscsi_base.ko module.