Lenovo DM120S, Installation And Cabling Manual, Page: 44 / 70

For example: 1a/2b, 2a/3b, 3a/1d,1c/2d, 2c/3d, 3c/1b.
Note: For an HA pair, the list of port pairs you identify for the first controller is also applicable to the
second controller.
• When cabling your system, you can use port pairs in the order in which you identified them or you can skip
port pairs:
– Use port pairs in the order in which you identified (listed) them when all port pairs are needed to cable
the stacks in your system. For example, if you identified six port pairs for your system and you have six
stacks to cable as multipath, you cable the port pairs in the order in which you listed them:
1a/2b, 2a/3b, 3a/1d,1c/2d, 2c/3d, 3c/1b
– Skip port pairs (use every other port pair) when not all port pairs are needed to cable the stacks in your
system. For example, if you identified six port pairs for your system and you have three stacks to cable
as multipath, you cable every other port pair in your list:
Note: When you have more port pairs than you need to cable the stacks in your system, the best
practice is to skip port pairs to optimize the SAS ports on your system. By optimizing SAS ports, you
optimize your system's performance.
Controller-to-stack cabling worksheets are convenient tools for identifying and organizing port pairs so that
you can cable the controller-to-stack connections for your HA pair configuration.
Chapter 8 “Controller-to-stack cabling worksheet template for multipathed connectivity” on page 43
Chapter 10 “Controller-to-stack cabling worksheet template for quad-pathed connectivity” on page 49
DM3000x, DM5000x, or DM7000x controller 0b and 0a port connection rules to external disk shelves
The DM3000x, DM5000x, or DM7000x has a unique set of connection rules because each controller must
maintain same domain connectivity between the internal storage (port 0b) and the stack. This means that
when a controller is located in slot A of the chassis (controller 1) it is in domain A (IOM A) and therefore port
0b must connect to IOM A in the stack. When a controller is located in slot B of the chassis (controller 2) it is
in domain B (IOM B) and therefore port 0b must connect to IOM B in the stack.
Note: If you do not connect the 0b port to the correct domain (cross-connect domains), you expose your
system to resiliency issues that prevent you from performing nondisruptive procedures safely.
• Controller 0b port (internal storage port):
– Controller 1 0b port always connects to IOM A (domain A).
– Controller 2 0b port always connects to IOM B (domain B).
– Port 0b is always the primary path.
– Port 0b always connects to the logical last disk shelf in a stack.
– Port 0b always connect to disk shelf IOM port 3.
• Controller 0a port (internal HBA port):
– Controller 1 0a port always connects to IOM B (domain B).
– Controller 2 0a port always connects to IOM A (domain A).
– Port 0a is always the secondary path.
– Port 0a always connects to the logical first disk shelf in a stack.
– Port 0a always connect to disk shelf IOM port 1.
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Installation and Cabling Guide for DM120S, DM240S, and DM600S