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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 .
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 the
multiple paths are to the same storage.
IP Storage has two additional features to provide HA solution in this scenario.
•
•
Statically imported iSCSI targets have an additional option to provide a secondary pWWN for the Fibre
Channel target. This can be used when the physical Fibre Channel target is configured to have an LU
visible across redundant ports. When the active port fails, the secondary port becomes active and the
iSCSI session switches to use the new active port (see
Figure 35-15 Static Target Importing Through Two Fibre Channel Ports
iSCSI host
iSCSI
In
Figure
provide redundant access to the Fibre Channel targets.
The failover to secondary port is done transparently by the IPS port without impacting the iSCSI session
from the host. All outstanding I/O are terminated with a check condition status when the primary port
fails. New I/O received while the failover has not completed will receive a busy status.
Tip
If you use LUN mapping, you can define a different secondary Fibre Channel LUN if the LU number is
different.
Enable the optional revert-primary-port option to direct the IPS port to switch back to the primary port
when the primary port is up again. If this option is disabled (default) and the primary port is up again
after a switchover, the old sessions will remain with the secondary port and does not switch back to the
primary port. However, any new session will use the primary port. This is the only situation when both
the primary and secondary ports are used at the same time.
To create a static iSCSI virtual target, follow these steps:
Command
Step 1
switch# config terminal
switch(config)#
Step 2
switch(config)# iscsi virtual-target name
iqn.1987-02.com.cisco.initiator
Cisco MDS 9000 Family Configuration Guide
35-40
IPS ports support VRRP protocol (see the
section on page
37-16) to provide failover for IPS ports.
IPS has transparent Fibre Channel target failover feature for iSCSI static virtual target.
Switch 1
IP
Network
Fibre Channel storage
35-15, you can create a iSCSI virtual target that is mapped to both pWWN1 and pWWN2 to
"Configuring VRRP for Gigabit Ethernet Interfaces"
Figure
Fibre Channel storage
pWWN 1
FC
pWWN 2
Primary access = pWWN1
Secondary access = pWWN 2
ABC
Chapter 35
Configuring iSCSI
35-15).
26:00:01:02:03:04:05:06
26:00:01:02:03:10:11:12
Purpose
Enters configuration mode.
Creates the iSCSI target name
iqn.1987-02.com.cisco.initiator.
OL-6973-03, Cisco MDS SAN-OS Release 2.x
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