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

Planning the networks 2–17
Figure 2-10 Incorrect physical HP SFS connections in dual-link server to single-link client nodes
configuration
In the configuration shown in Figure 2-10, client nodes 7 through 12 will typically all be able to perform
I/O operations at the same time, to the limit of the network interfaces (in this case 600 MB/sec). However,
if all client nodes perform I/O operations to Object Storage Servers 1 through 3 at the same time, the
maximum observed throughput will be approximately 200MB/sec, because this is the limit of the bottleneck
that would occur between the two switches (as highlighted in Figure 2-10). In a correct configuration, the
throughput from the same three Object Storage Servers would be approximately 300MB/sec.
2.4.2.3 Bonded Gigabit Ethernet network considerations
To realize the benefits that bonded Gigabit Ethernet can provide, the network must be set up correctly. In
addition to the considerations mentioned in Section 2.4.2.1, there are a number of bonding-specific
considerations.
Bonded devices operate in one of two mutually exclusive modes:
• 802.3ad (the default): Also known as Link Aggregation Control Protocol (LACP), this is the default
mode and requires that the switch is configured to support it. The ports must be configured to be on
the same network as the client nodes. This configuration is switch-specific and not all switches support
this mode of operation (see Appendix H for additional information).
• balance-alb: In this mode, the switch must be configured so that all of the server ports are on the
same network as the client nodes and the server ports must not be trunked or bonded by the switch.
For all bonded modes, there is a bonding master device (bond0) and constituent slave devices (eth2,
eth3). The master device is configured as an ordinary Ethernet device. All constituent ports of a bond must
be on the same logical network. In the case of 802.3ad bonding, the switch must be configured to
trunk/bond each server's interconnect links. For balance-alb bonding, the switch needs no special
configuration, except that all servers and links must be on the same logical network.
When HP SFS systems are installed, the system software assumes that any bonded Gigabit Ethernet networks
use the 802.3ad mode. You can change this later if necessary, by changing the bonding_options
attribute. For information on how to change this attribute, refer to Chapter 7 of the HP StorageWorks
Scalable File Share System User Guide.