10–iSCSI Protocol
iSCSI Offload in Windows Server
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iSCSI Offload in Windows Server
iSCSI traffic may be segregated offload is a technology that offloads iSCSI
protocol processing overhead from host processors to the iSCSI host bus adapter
to increase network performance and throughput while helping to optimize server
processor use. This section covers Windows iSCSI offload feature for the 8400
Series family of network adapters.
iSCSI Offload Limitations
The bnx2i driver for iSCSI does not operate on a stand-alone PCI device. It
shares the same PCI device with the networking driver (bnx2 and bnx2x). The
networking driver alone supports layer 2 networking traffic. Offloaded iSCSI
operations require both the networking driver and the bnx2i driver.
iSCSI operations will be interrupted when the networking driver brings down or
resets the device. This scenario requires proper handling by the networking and
bnx2i drivers, and the userspace iscsid daemon that keeps track of all iSCSI
sessions. Offloaded iSCSI connections take up system and on-chip resources that
must be freed up before the device can be reset. iscsid running in userspace is
generally less predictable, as it can run slowly and take a long time to disconnect
and reconnect iSCSI sessions during network reset, especially when the number
of connections is large. QLogic cannot guarantee that iSCSI sessions will always
recover in every conceivable scenario when the networking device is repeatedly
being reset. QLogic recommends that administrator-administered network device
resets, such as MTU change, ring size change, device shutdown, hot-unplug, and
so forth, be kept at a minimum while there are active offloaded iSCSI sessions
running on that shared device. On the other hand, link-related changes do not
require device reset and are safe to be performed at any time.
To help alleviate some of the above issues, install the latest open-iscsi utilities by
upgrading your Red Hat Network subscription.
Configuring iSCSI Offload
With the proper iSCSI offload licensing, you can configure your iSCSI-capable
8400 Series network adapter to offload iSCSI processing from the host processor.
The following process enables your system to take advantage of QLogic’s iSCSI
offload feature.
Installing QLogic Drivers and Management Applications
Installing the Microsoft iSCSI Initiator
Configuring QLogic iSCSI Using QCS
Summary of Contents for 8400 Series
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