HP StorageWorks X5500 Network Storage Gateway for Linux setup guide (AP811-96003, October 2009)

• Fibre Channel switch-based fencing (also called “fabric fencing”): When a server needs to be
fenced, HP X5500 Storage Gateway for Linux disables the server’s access in the Fibre Channel
fabric.
• Web management-based fencing (also called “server-based fencing”): HP X5500 Storage Gateway
for Linux uses remote management hardware on the server to reset or power off the server. (HP
ProLiant servers (except the 1xx series) support this kind of fencing using iLO remote management
functionality.)
For sites using fabric fencing, the Fibre Channel switches must be configured as described below to
enable cluster operations across the SAN. Configuring the Fibre Channel switches is not required for
sites using server-based fencing. However, certain HP X5500 Storage Gateway for Linux commands
can return more information if the switches are configured as described herein.
To configure Fibre Channel switches, complete the following tasks:
• Modify the SNMP setup. Make the following changes:
• Enable access to the SNMP agent from each server that will be in the cluster.
• Set the SNMP community string to the desired value. The community string must be the same
for all Fibre Channel switches. If you are using fabric fencing, ensure that the community string
has write privileges. For server-based fencing, you can optionally configure a read-only com-
munity string.
• On Brocade switches only, run the snmpMibCapSet command on the switch. Change the
famib setting to yes and accept the default values for the other settings.
• If the servers are connected to switches in multiple fabrics, the physical ports on each switch must
be assigned to unique domain IDs. A different domain ID must be used on each fabric (any given
domain ID can exist on only one fabric in the SAN). For example, if a server is connected to two
switches that are not in the same fabric, switch1 could use domain ID 6 and switch2 could use
domain ID 7. Domain ID 6 must not exist on the fabric containing switch2 and domain ID 7 must
not exist on the fabric containing switch1.
Typically these tasks can be performed from the Fibre Channel switch or from third-party applications.
See your Fibre Channel switch or application documentation for more information. For EMC PowerPath,
see the PowerPath documentation for zoning requirements.
4. Obtain HBA WWID strings
Before the storage subsystem can be fully configured, you need to know the WWIDs of the HBAs for
each node in the cluster.
This is required so that the LUNs from the storage arrays can be presented to all of the nodes (assuming
some kind of selective presentation mechanism is enabled on the arrays). There are numerous techniques
used for performing this task. Here are two alternatives:
• Enable the HBA on each node one by one and use the array management software to recognize
the new initiators. This is typically done by loading and unloading the HBA driver. The following
commands can be used to accomplish this task:
• Load the HBA driver: /etc/init.d/pmxs load
• Unload the HBA driver: /etc/init.d/pmxs unload
The configuration file for the HBA driver is /etc/opt/polyserve/fc_pcitable. The inform-
ation in this file is used to load the HBA driver module.
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