7914Cabling2-1908.fm Draft Document for Review March 28, 2011 12:24 pm
102 IBM System Storage DS3500: Introduction and Implementation Guide
4.6.3 Single controller DS3500 with one or more EXP3500 enclosures
Figure 4-16 shows the SAS connections between a single controller DS3500 subsystem and
three EXP3500 enclosures, with a single ESM installed in each EXP3500. You should use the
two connection rules above to connect the SAS ports on the DS3500 and the EXP3500s as
shown.
Figure 4-16 EXP3500 attachment - single controller and single ESM configuration
4.6.4 Dual controller DS3500 with one EXP3500 enclosure
In this section we describe how to correctly cable a dual controller DS3500 to a single
EXP3500 enclosure with two ESMs installed. This configuration provides redundancy on the
drive-side connections. Figure 4-17 on page 103 shows the SAS cable connections in this
configuration.
Note: The configuration shown in Figure 4-16 is a fully functional configuration but there is
no redundancy on the drive side connections. If there is a fault with any one of the
EXP3500 enclosures or the ESMs or a SAS cable, then there will be a loss of connection
to the drives in all the EXP3500s that are connected below the point of failure. This
situation can be avoided by using a configuration with two controllers in the DS3500 and
two ESMs installed in each EXP3500 that is connected to the DS3500.
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