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    <title>iSCSI HA with Host Not Having Any Multi-Path Software </title>
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<a name="wp1088294"> </a><h1 class="pTitle">
iSCSI HA with Host Not Having Any Multi-Path Software

</h1>
<a name="wp1088295"> </a><p class="pBody">
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.

</p>
<a name="wp1088297"> </a><p class="pBody">
IP storage has two additional features that provide an HA solution in this scenario.

</p>
<div class="pSmartList1"><ul class="pSmartList1">
<a name="wp1088300"> </a><li class="pSmartList1">IPS ports support the VRRP feature
</li>
<a name="wp1088302"> </a><li class="pSmartList1">IPS has transparent Fibre Channel target failover for iSCSI static virtual targets.
</li>
</ul></div>
<a name="wp1088304"> </a><p class="pBody">
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 .

</p>
<a name="wp1088319"> </a><p class="pBody">
The failover to a secondary port is done transparently by the IPS port without impacting the iSCSI 
session from the host. All outstanding I/Os are terminated with a check condition status when the 
primary port fails. New I/Os received during the failover are not completed and receive a busy status.

</p>
<a name="wp1088321"> </a><p class="pBodyAutonumRel">
<strong>Tip	&nbsp;&nbsp;&nbsp;</strong> If you use LUN mapping, you can define a different secondary Fibre Channel LUN if the LU number is 
different.

</p>
<a name="wp1088322"> </a><p class="pBody">
Enable the optional<b class="cBold"> revert-primary-port</b> 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 do 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.

</p>
<hr /><br><p class="pBody">Copyright 2010-2013, Cisco Systems, Inc. All rights reserved.</p> 

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