Chelsio Communications Chelsio T5 Installation And User Manual page 100

Chapter VII. iSCSI PDU Offload Target
T440-LP-CR
T420-BT
T420-LL-CR
T420-CX
1.2.2. Adapter Requirements
The Chelsio iSCSI PDU Offload Target software can be used with or without hardware protocol
offload technology. There are four 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.
TOE HW Acceleration – In TOE mode the software takes advantage of the TCP/IP Offload
capability of Chelsio's TOE adapter (without the additional benefit of iSCSI HW
acceleration).
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.
Mix of iSCSI HW Acceleration and TOE HW Acceleration – Using a special software mode
the stack can be configured to change between iSCSI acceleration or just TOE acceleration,
depending if digests are used or not.
1.2.3. 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.
Chelsio T5/T4 Unified Wire For Linux
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