iSCSI High Availability
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
Each IPS ports is exporting the same two Fibre Channel target ports of the storage but as different iSCSI
target names if you use dynamic iSCSI targets). So the two IPS ports are exporting a total of four iSCSI
target devices. These four iSCSI targets map the same two ports of the Fibre Channel target.
The iSCSI host uses NIC-1 to connect to IPS port 1 and NIC-2 to connect to IPS port 2. Each IPS port
exports two iSCSI targets, so the iSCSI host creates four iSCSI sessions.
If the iSCSI host NIC-1 fails (see
still have sessions 3 and 4.
If the IPS port 1 fails, the iSCSI host cannot connect to the IPS port, and sessions 1 and 2 fail. But
sessions 3 and 4 are still available.
If the storage port 1 fails, then the IPS ports will terminate sessions 1 and 3 (put iSCSI virtual target
iqn.com.cisco.mds-5.1-2.p1 and iqn-com.cisco.mds-5.1-1.p1 in offline state). But sessions 2 and 4 are
In this topology, you have recovery from failure of any of the components. The host multi-path software
takes care of load-balancing or failover across the different paths to access the storage.
iSCSI HA with Host Not Having Any Multi-Path Software
The above topology will not work if the host does not have multi-path software because the host has
multiple sessions to the same storage. Without multi-path software the host does not have knowledge of
the multiple paths to the same storage.
Cisco MDS 9000 Family CLI Configuration Guide
Host Running Multi-Path Software
for the physical view), then sessions 1 and 2 fail but we
OL-16184-01, Cisco MDS SAN-OS Release 3.x