Chapter 3: Subsystem Connection
3-7
IMPORTANT:
1.
One drawback of using the hub function is that the host ports
looped together may not be connected to the N_ports on a fabric
switch. When host ports are hubbed together, they are ideal for
connecting direct-attached servers with path redundancy while
without the costs on expensive FC switches.
2.
Another drawback is that if host ports are hubbed together, e.g.,
controller A CH0 ports with controller B CH0 ports, the
combined host ports’ bandwidth is halved.
For example, the CH0 host ports on each controller feature a
4Gb/s bandwidth and a total of 8Gb/s bandwidth from the CH0
host ports on two controllers.
If host ports are hubbed together, all four CH0 host ports share a
4Gb/s bandwidth.
2.
Enclosure ID
: For a RAID subsystem the default is “0” and needs not
be changed. As diagrammed below, if the RAID subsystem is
connected with Rorke’s SAS interface JBODs, each JBOD enclosure
should have an enclosure ID starting from #
1
.
Shown below are a primary RAID enclosure connected with SAS
expansion JBODs via SAS external wide links. The enclosure IDs on
expansion JBODs are configured using a rotary ID switch.
Figure 3-4: Enclosure ID Sequence