White Papers

iSCSI Optimization
This chapter describes how to congure internet small computer system interface (iSCSI) optimization, which enables quality-of-service
(QoS) treatment for iSCSI trac. The topics covered in this chapter include:
• iSCSI Optimization Overview
• Default iSCSI Optimization Values
• iSCSI Optimization Prerequisites
• Conguring iSCSI Optimization
• Displaying iSCSI Optimization Information
Topics:
• iSCSI Optimization Overview
• Default iSCSI Optimization Values
• iSCSI Optimization Prerequisites
• Conguring 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-conguration of several key
network congurations that enables optimization of the network for better storage trac throughput. iSCSI is disabled by default.
iSCSI optimization also provides a means of monitoring iSCSI sessions and applying quality of service (QoS) policies on iSCSI trac. 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 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 congure 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 conguration to detect Compellent storage arrays where auto-detection is not supported.
• Automatic conguration of switch ports after detection of storage arrays.
• If you congure ow-control, iSCSI uses the current conguration. If you do not congure ow-control, iSCSI auto-congures ow
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-congured iSCSI class of service (CoS) prole is applied to all iSCSI trac. Classier rules are used to direct the
iSCSI data trac 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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