Reference Guide

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iSCSI Optimization
iSCSI optimization is supported on the S4820T platform.
This chapter describes how to configure internet small computer system interface (iSCSI) optimization, which enables
quality-of-service (QoS) treatment for iSCSI traffic. The topics covered in this chapter include:
• iSCSI Optimization Overview
• Default iSCSI Optimization Values
• iSCSI Optimization Prerequisites
• Configuring iSCSI Optimization
• Displaying iSCSI Optimization Information
iSCSI Optimization Overview
iSCSI is a TCP/IP-based protocol for establishing and managing connections between IP-based storage devices and
initiators in a storage area network (SAN).
iSCSI optimization enables the network switch to auto-detect Dell’s iSCSI storage arrays and triggers a self-
configuration of several key network configurations that enables optimization of the network for better storage traffic
throughput. iSCSI is disabled by default on the S4820T platform and is not supported on the Z9000 platform.
iSCSI optimization also provides a means of monitoring iSCSI sessions and applying quality of service (QoS) policies on
iSCSI traffic. When enabled, iSCSI optimization allows a switch to monitor (snoop) the establishment and termination of
iSCSI connections. The switch uses the snooped information to detect iSCSI sessions and connections established
through the switch.
iSCSI optimization allows you to reduce deployment time and management complexity in data centers. In a data center
network, Dell EqualLogic and Compellent iSCSI storage arrays are connected to a converged Ethernet network using the
data center bridging exchange protocol (DCBx) through stacked and/or non-stacked Ethernet switches.
iSCSI session monitoring over virtual link trunking (VLT) synchronizes the iSCSI session information between the VLT
peers, allowing session information to be available in both the VLT peers. You can enable or disable iSCSI when you
configure VLT.
iSCSI optimization functions as follows:
• Auto-detection of EqualLogic storage arrays — the switch detects any active EqualLogic array directly attached
to its ports.
• Manual configuration to detect Compellent storage arrays where auto-detection is not supported.
• Automatic configuration of switch ports after detection of storage arrays.
• If you configure flow-control, iSCSI uses the current configuration. If you do not configure flow-control, iSCSI
auto-configures flow control settings so that receive-only is enabled and transmit-only is disabled. .
• iSCSI monitoring sessions — the switch monitors and tracks active iSCSI sessions in connections on the switch,
including port information and iSCSI session information.
• iSCSI QoS — A user-configured iSCSI class of service (CoS) profile is applied to all iSCSI traffic. Classifier rules
are used to direct the iSCSI data traffic to queues that can be given preferential QoS treatment over other data
passing through the switch. Preferential treatment helps to avoid session interruptions during times of
congestion that would otherwise cause dropped iSCSI packets.
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