HP StorageWorks Scalable File Share System Installation and Upgrade Guide Version 2.2

Planning the networks 2–13
There are two supported configurations for the use of multiple Gigabit Ethernet links:
• Symmetric: Dual server links with dual client node links (see Section 2.4.2.2.1)
• Asymmetric: Dual server links with single client node links (see Section 2.4.2.2.2)
NOTE: It is possible to use both single and dual-link client nodes with the same HP SFS system if all
networks are correctly configured; if you choose to use such a configuration, HP recommends that you
apply the rules for the asymmetric setup (because they are more restrictive), and then configure the
dual-link client nodes as described for symmetric configurations.
There are a number of common requirements between these two configurations, and also a number of
configuration-specific requirements. In all cases, the network must be reliable and the interconnecting switch
hardware capable of sustained performance either up to or above the level of performance expected of the
HP SFS system.
Requirements
To ensure optimum network performance, the requirements that are common to all supported dual Gigabit
Ethernet configurations are as follows:
• Server interfaces must be configured on separate logical networks.
• Interfaces on the same logical network must be connected via the fastest possible pathway through
any intermediary hardware.
• Identically addressed non-interconnect networks on client nodes must be excluded from use when
mounting file systems.
• The lnet options settings on the client nodes must be correctly configured to allow the nodes to
access the appropriate server network. For more information on lnet options settings, refer to
Appendix B in the HP StorageWorks Scalable File Share Client Installation and User Guide.
Recommendations
In addition to the requirements listed above, there are a number of best practice guidelines that will help
you to design the network to ensure the correct configuration and optimal performance of a dual Gigabit
Ethernet HP SFS installation:
• Where possible, match server and client interconnect interfaces by network and netmask.
• Use as few intermediary links as possible to fully connect the servers and clients.
• Do not use routers in the network between client systems and servers.
Note that in a dual-link configuration, connectivity is initially lost with the loss of a single link. The client
node will disconnect both links and will then be able to reconnect using just a single link. However, there is
no guarantee that the network loss will be transparent to any application performing I/O operations to a
file system; as a result, an I/O error may be passed to the application.