Configuring Islb - HP Cisco MDS 9216 - Fabric Switch Configuration Manual

Chapter 50 Configuring iSCSI
S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m
Table 50-1
Mode
Pass-thru
Store-and-forward
Cut-thru
Changing the forwarding mode of an iSCSI interface that is part of an iSLB VRRP group impacts load
Caution
balancing on the interface. See the
Balancing" section on page

Configuring iSLB

The iSCSI server load balancing (iSLB) feature provides a means to easily configure large scale iSCSI
deployments containing hundreds or even thousands of initiators. When not using iSLB, configuring
iSCSI requires the following:
•
•
•
iSLB provides the following features:
•
•
OL-16184-01, Cisco MDS SAN-OS Release 3.x
Comparison of iSCSI Routing Modes
Advantages
Low-latency
Data digest can be used
Higher data transfer
performance
Improved read performance
over store-and-forward
50-45.
You need to perform multiple configuration steps on the MDS switch, including the following:
– Initiator configuration using static pWWN and VSAN.
– Zoning configuration for initiators and targets.
– Optional create virtual target and give access to the initiator.
Configuration of target LUN mapping and masking on the storage system for the initiator based
–
on the static pWWN created for the initiator on the MDS switch.
You need to duplicate the configuration manually on multiple MDS switches.
There is no load balancing for IPS ports. For example:
The Virtual Router Redundancy Protocol (VRRP) only supports active and backup, not load
–
balancing.
– You must use multiple VRRP groups and configure hosts in different groups.
The iSLB initiator configuration is simplified with support for initiator targets and auto-zones.
Cisco Fabric Services (CFS) eliminates the need for manual configuration by distributing the iSLB
initiator configuration among all MDS switches in the fabric.
Disadvantages
Lower data transfer performance.
Data digest cannot be used.
If the Fibre Channel target sent read data for
different commands interchangeably, data of the
first command is forwarded in cut-thru mode but
the data of subsequent commands is buffered
and the behavior is the same as
store-and-forward mode.
Data digest cannot be used.
"Changing iSCSI Interface Parameters and the Impact on Load
Cisco MDS 9000 Family CLI Configuration Guide
Configuring iSLB
50-35