User guide

 If you choose balance, Xsan writes data to the storage pool that has the most free
space.
Planning the Ethernet TCP/IP Network
Ethernet connections are used in several ways in an Xsan SAN:
Xsan clients and metadata controllers use Ethernet to exchange volume metadata. Â
Xsan clients can use Ethernet for access to networks outside the SAN (campus or Â
corporate intranet or the Internet).
Xsan metadata controllers can use Ethernet connections for remote management. Â
RAID systems can use Ethernet connections for system management. Â
Fibre Channel switches can use Ethernet connections for switch management. Â
You have two options:
Use one Ethernet network for all trac. This is the less expensive option, but is also Â
less secure and might not provide the best performance.
Use two separate networks—one for metadata and another for all other IP trac. Â
This conguration is slightly more expensive (requiring two Ethernet adapters for
each computer and an additional switch) but oers greater security and better
performance because routine network trac doesn’t interfere with SAN volume
metadata trac.
Using a Private Metadata Network
Non–SAN-related Ethernet trac 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 le system performance. Similarly,
using the same Ethernet network to connect client computers to directory services
and SAN metadata can aect SAN performance.
If SAN performance is critical for your users or applications, keep all extraneous trac
o 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 trac, 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.
Using Switches Instead of Hubs
To get the best performance, use Gigabit Ethernet switches, not hubs, in the SAN
metadata network.
32 Chapter 2 Planning a Storage Area Network