Chapter 2: Installing the Chassis
Connect the RAID Chassis and Expansion Chassis
QX and QXS Setup Guide
72
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QXS-5600 base does not support QXS-1200/QXS-2400 expansions.
Cabling
The QXS Storage supports both straight-through and reverse SAS cabling. Reverse cabling allows any
drive chassis to fail or be removed while maintaining access to other chassis. Fault tolerance and
performance requirements determine whether to optimize the configuration for high availability or high
performance when cabling.
Caution:
Some 6-Gbit/s drives might not consistently support a 6-Gbit/s transfer rate. If this happens,
the system automatically adjusts transfers to those drives to 3-Gbit/s, increasing reliability and reducing
error messages with little impact on system performance. This rate adjustment persists until the
controller is restarted or power-cycled.
Cabling diagrams in this section show fault-tolerant cabling patterns. Controller and expansion modules are
identified by
<enclosure-ID><controller-ID>
. When connecting multiple drive chassis, use reverse
cabling to ensure the highest level of fault tolerance, enabling controllers to access remaining expansion
chassis if a expansion chassis fails.
For example, Figure 76 on page 77 shows reverse cabling wherein controller 0A (i.e., enclosure-ID = 0;
controller-ID = Able) is connected to expansion module 1A, with a chain of connections cascading down
(blue). Controller 0B is connected to the lower expansion module (B) of the last expansion chassis in the
chain, with connections moving in the opposite direction (green). Several cabling examples are provided on
the following pages.
Note:
The QXS storage RAID chassis and expansion chassis support hot-plug replacement of
redundant controller modules, fans, power supplies, and IOMs. Hot-add of expansion chassis is also
supported.
Cable Requirements for Expansion Chassis
The expansion chassis support 6-Gbit/s or 3-Gbit/s expansion port data rates. Use only OEM-qualified
cables, and observe the following guidelines:
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When installing SAS cables to expansion I/O modules, use only supported mini-SAS x4 cables with
SFF-8644 connectors.
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Qualified mini-SAS to mini-SAS 0.5 m (1.64') cables are used to connect cascaded expansion chassis in
the rack. The “HD mini-SAS to HD mini-SAS” cable designator connotes SFF-8644 to SFF-8644
connectors.
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The maximum expansion cable length allowed in any configuration is 2 m (6.56').
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Cables required, if not included, must be separately purchased.
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When adding more than two expansion chassis, you may need to purchase additional 1 m or 2 m cables,
depending upon number of expansion chassis and cabling method used:
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Spanning 3, 4, or 5 expansion chassis requires 1 m (3.28') cables.
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Spanning 6 or 7 expansion chassis requires 2 m (6.56') cables.
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You may need to order additional or longer cables when reverse-cabling a fault-tolerant configuration.
