User guide

NetXtreme II User Guide
September 2013
Broadcom Corporation
Page 98 iSCSI Crash Dump Document INGSRVT78-CDUM100-R
ISCSI CRASH DUMP
If you will use the Broadcom iSCSI Crash Dump utility, it is important to follow the installation procedure to install the iSCSI
Crash Dump driver. See Using the Installer for more information.
ISCSI OFFLOAD IN WINDOWS SERVER
iSCSI 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 utilization.
This section covers Windows iSCSI offload for the NetXtreme II family of network adapters. For Linux iSCSI offload, see
Linux iSCSI Offload.
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, as well as 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. Broadcom cannot
guarantee that iSCSI sessions will always recover in every conceivable scenario when the networking device is repeatedly
being reset. Broadcom 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.