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Part (A) of
Figure 3-2
shows server S
a switched pair of FL_Ports communicating at 1.0625 Gbps. Server S
is connected to device D
also communicating at 1.0625 Gbps. Because of opportunistic
bandwidth sharing, the two switched pairs effectively increase the
switch bandwidth to 2.1250 Gbps. The remaining ports are available
for switched connection to each other but cannot communicate with
servers S
and S
or devices D
1
2
the logical equivalent of this arbitrated loop.
Switched mode operation provides the ability to design a complex
and high-performance SAN for the department or workgroup.
Consider the following when planning such a SAN:
•
Connect loop switch ports to multiple unmanaged hubs to
provide additional FC-AL device connectivity in the form of
looplets. Cascade the unmanaged hubs if more hubs are
necessary for the configuration.
•
Attach devices that frequently communicate with each other to
the same looplet to take advantage of opportunistic bandwidth
sharing (communication predominately stays within the loop).
Switched connections allow connectivity as necessary to devices
attached to other looplets.
•
Each looplet acts as a normal FC-AL loop. Spread multiple
servers and high bandwidth storage devices across several
looplets to avoid performance problems associated with a single
looplet.
•
Consider data traffic capacity of the department or workgroup
(normal and peak load) as part of the switch planning and
installation process. Capacity planning:
— Ensures loop traffic is distributed and balanced across servers
and storage devices.
— Identifies traffic bottlenecks and provides for alternate
connectivity solutions if required.
— Assists in calculating scalability to satisfy nondisruptive
growth requirements or eventual connection to a Fibre
Channel switched fabric.
Capacity planning is a dynamic activity that must be performed
when new devices, applications, or users are added to the
department or workgroup loop configuration.
Planning Considerations for Fibre Channel Topologies
Planning Considerations for Fibre Channel Topologies
connected to device D
1
through a second switched pair of ports,
2
and D
. Part (B) of
1
2
through
1
2
Figure 3-2
shows
3-5
3
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