Deployment Guide

12 Gb HD mini-SAS host connection
To connect controller modules supporting HD mini-SAS host interface ports to a server HBA, using the SFF-8644 dual HD
mini-SAS host ports on a controller, select a qualified HD mini-SAS cable option. For information about configuring SAS HBAs,
see the SAS topics under Perform host setup on page 43.
A qualified SFF-8644 to SFF-8644 cable option is used for connecting to a 12Gb/s enabled host. Qualified SFF-8644 to
SFF-8644 options support cable lengths of 0.5 m (1.64'), 1 m (3.28'), 2 m (6.56'), and 4 m (13.12').
Connecting direct attach configurations
A dual-controller configuration improves application availability. If a controller failure occurs, the affected controller fails over to
the healthy partner controller with little interruption to data flow.
A failed controller can be replaced without the need to shut down the storage system.
NOTE: In the following examples, a single diagram represents CNC, SAS, and 10Gbase-T host connections for ME4 Series
controller enclosures. The location and sizes of the host ports are similar. Blue cables show controller A paths and green
cables show controller B paths for host connection.
Single-controller module configurations
A single controller module configuration does not provide redundancy if a controller module fails.
This configuration is intended only for environments where high availability is not required. If the controller module fails, the host
loses access to the storage data until failure recovery actions are completed.
NOTE: Expansion enclosures are not supported in a single controller module configuration.
Figure 19. Connecting hosts: ME4 Series 2U direct attach – one server, one HBA, single path
1. Server
2. Controller module in slot A
3. Controller module blank in slot B
NOTE:
If the ME4 Series 2U controller enclosure is configured with a single controller module, the controller module must
be installed in the upper slot. A controller module blank must be installed in the lower slot. This configuration is required to
enable sufficient air flow through the enclosure during operation.
Dual-controller module configurations
A dual-controller module configuration improves application availability.
If a controller module failure occurs, the affected controller module fails over to the partner controller module with little
interruption to data flow. A failed controller module can be replaced without the need to shut down the storage system.
In a dual-controller module system, hosts use LUN-identifying information from both controller modules to determine the data
paths are available to a volume. Assuming MPIO software is installed, a host can use any available data path to access a volume
that is owned by either controller module. The path providing the best performance is through the host ports on the controller
module that owns the volume . Both controller modules share one set of 1,024 LUNs (0-1,023) for use in mapping volumes to
hosts.
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Cable host servers to the storage system