Isl Transfer Rate Versus Fabric Port Availability (Two-Director Fabric) - HP StorageWorks 64 - SAN Director Switch Planning Manual

Planning Considerations for Fibre Channel Topologies
Table 2: ISL Transfer Rate versus Fabric Port Availability (Two-Director Fabric)
Number
of ISLs
1
2
3
4
5
6
7
8
■
82
ISL Data Transfer
Rate (at 1.0625 Gbps)
1.0625 Gbps
2.1250 Gbps
3.1875 Gbps
4.2500 Gbps
5.3125 Gbps
6.3750 Gbps
7.4375 Gbps
8.5000 Gbps
Load balancing — Planning consideration must be given to the amount of
data traffic expected through the fabric or through a fabric element. Because
the fabric automatically determines and uses the least cost (shortest) data
transfer path between source and destination ports, some ISL connections
may provide insufficient bandwidth while the bandwidth of other connections
is unused. For additional information, refer to
Implications" on page 107.
Fibre Channel frames are routed through fabric paths that implement the
minimum possible hop count. For example, in
between devices connected to Director S
directly through ISLs that connect the directors (one hop). No traffic is routed
through Director S (two hops). If heavy traffic between the devices is
3
expected, multiple ISL connections should be configured to create multiple
minimum-hop paths. With multiple paths, the directors balance the load by
assigning traffic from different ports to different minimum-hop paths (ISLs).
When balancing a load across multiple ISLs, a director or switch attempts to
avoid assigning multiple ports attached to a device to the same ISL. This
minimizes the probability that failure of a single ISL will affect all paths to the
device. However, because port assignments are made incrementally as devices
log into the fabric and ISLs become available, optimal results are not
guaranteed.
ISL Data Transfer Rate
(at 2.125 Gbps)
2.1250 Gbps
4.2500 Gbps
6.3750 Gbps
8.5000 Gbps
10.6250 Gbps
12.7500 Gbps
14.8750 Gbps
17.0000 Gbps
"Large Fabric Design
Figure 35 on page 78, all traffic
and Director S
1
SAN High Availability Planning Guide
Available
Fabric Ports
126
124
122
120
118
116
114
112
communicates
2