Single Controller Ds3500 With One Or More Exp3500 Enclosures; Dual Controller Ds3500 With One Exp3500 Enclosure - IBM System Storage DS3500 Introduction And Implementation Manual

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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
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.

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.
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IBM System Storage DS3500: Introduction and Implementation Guide
Draft Document for Review March 28, 2011 12:24 pm