Apple Xsan 2 - Manual (Page 52)

Use a private metadata network
Non–SAN-related Ethernet traffic can interfere with the exchange of metadata
among Xsan controllers and clients. For example, using the same connection for Xsan
metadata exchange and Internet access can slow file system performance. Similarly,
using the same Ethernet network to connect client computers to directory services
and SAN metadata can affect SAN performance.
If SAN performance is critical for your users or applications, keep all extraneous traffic
off the network that clients and metadata controllers use to exchange metadata. For
best SAN performance, set up a private Ethernet TCP/IP network for the exclusive use
of Xsan clients and metadata controllers. For other types of network traffic, including
Internet access, RAID system and Fibre Channel switch management, remote SAN
management, or directory services, connect each client and metadata controller to a
second Ethernet network using a second Ethernet port.
Use switches instead of hubs
To get the best performance, use Gigabit Ethernet switches, not hubs, in the SAN
metadata network.
Plan the Fibre Channel network
Xsan uses Fibre Channel connections to:
Transfer user data between clients and data storage pools Â
Transfer metadata between metadata controllers and metadata storage pools Â
If you have connections operating below the data rate supported by your equipment
(typically 2 or 4 Gb/s), verify Fibre Channel performance and troubleshoot the fabric.
Verify base Fibre Channel performance
Because the devices connected to a Fibre Channel network adjust their speed to
match the slowest device on the fabric, be sure that all connections in the fabric are
operating at the expected speed (typically 2 or 4 Gb/s).
Check Fibre Channel connection performance:
Use the management software provided with your Fibre Channel switches to test the
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performance of your Fibre Channel fabric.
If your Fibre Channel fabric is running slowly
If your Fibre Channel fabric isn’t running at the expected speed (typically 2 or 4 Gb/s,
depending on your equipment), review the following information.
52 Chapter 3 Plan a SAN