Users Guide

Table Of Contents
iSCSI Optimization
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
Topics:
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 Dells 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 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.
iSCSI DCBx TLVs are supported.
NOTE:
After a switch is reloaded, powercycled, or upgraded, any information exchanged during the initial handshake is not
available. If the switch establishes communication after reloading, it detects that a session was in progress but could not
obtain complete information for it. Any incomplete information is not available in the show commands.
NOTE: After a switch is reloaded, powercycled, or upgraded, the system may display the ACL_AGENT-3-
ISCSI_OPT_MAX_SESS_LIMIT_REACHED: Monitored iSCSI sessions reached maximum limit log
22
434 iSCSI Optimization