Dot Hill Systems II 200 FC - Manual (Page 59)

Chapter 4 Connecting Your Array 4-11
4.5 Cabling to Expansion Units
The instructions in this section apply to the SANnet II 200 FC and the SANnet II 200
SATA arrays only. The SANnet II 200 SATA SE array does not support expansion
units.
Caution – When connecting expansion units to a RAID array, always connect channel
2 of the RAID array to the A channel of the expansion units, and connect channel 3 of
the RAID array to the B channel of the expansion units. Otherwise, unexpected
behavior might occur.
Several cabling configurations are possible, each with its own advantages and
disadvantages. Refer to the SANnet II 200 FC and SATA Array Best Practices Manual
for more information about the suitability of various configurations for various
application requirements, as well as for information about high-capacity
configurations.
The maximum number of expansion units attached to a RAID array are:
■
up to eight SANnet II 200 FC expansion units attached to a SANnet II 200 FC array
■
up to five SANnet II 200 SATA expansion units attached to a SANnet II 200 SATA
array
■
up to five SANnet II 200 FC expansion units and SANnet II 200 SATA expansion
units, in any combination, attached to a SANnet II 200 FC array
These configurations are described in the SANnet II 200 FC and SATA Array Best
Practices Manual.
The examples in Figure 4-7 and Figure 4-8 show RAID arrays connected to two
expansion units. Connections to expansion units are designed to keep all A drive ports
on the same loop and all B drive ports on the same loop.
Caution – To avoid drive assignment conflicts, make sure that each connected array
and expansion unit uses a different loop ID, as described in “Setting Loop IDs on
Expansion Units” on page 4-13.
In the RAID array, two of the unused SFP host ports can be used to provide redundant
pathing to the two servers, and the remaining unused SFP host ports can be connected
to two more servers in a redundant configuration.
Similarly, you can connect expansion units to other channels (which are separate from
channels 2 and 3) if you configure them as drive channels. For details, refer to the
SANnet II Family RAID Firmware User’s Guide.