•
ME4 Series 2U controller enclosures support up to ten 2U enclosures (including the controller enclosure), or a maximum of 240 disk
drives.
•
ME4 Series 5U controller enclosures support up to four 5U enclosures (including the controller enclosure), or a maximum of 336 disk
drives.
•
ME4 Series expansion enclosures are equipped with dual-IOMs. These expansion enclosures cannot be cabled to a controller enclosure
equipped with a single IOM.
•
The enclosures support reverse SAS cabling for adding expansion enclosures. Reverse cabling enables any drive enclosure to fail—or
be removed—while maintaining access to other enclosures. Fault tolerance and performance requirements determine whether to
optimize the configuration for high availability or high performance when cabling.
Cable requirements for expansion enclosures
ME4 Series supports 2U12, 2U24, and 5U84 form factors, each of which can be configured as a controller enclosure or an expansion
enclosure. Key enclosure characteristics include:
NOTE:
To add expansion enclosures to an existing storage system, power down the controller enclosure before
connecting the expansion enclosures.
•
When connecting SAS cables to IOMs, use only supported HD mini-SAS x4 cables.
•
Qualified HD mini-SAS to HD mini-SAS 0.5 m (1.64 ft.) cables are used to connect cascaded enclosures in the rack.
•
The maximum enclosure cable length that is allowed in any configuration is 2 m (6.56 ft.).
•
When adding more than two expansion enclosures, you may need to purchase additional cables, depending upon the number of
enclosures and cabling method used.
•
You may need to order additional or longer cables when reverse-cabling a fault-tolerant configuration.
Per common convention in cabling diagrams, the controller enclosure is shown atop the stack of connected expansion enclosures. In
reality, you can invert the order of the stack for optimal weight and placement stability in the rack. The schematic representation of
cabling remains unchanged. See
Mount the enclosures in the rack
When connecting multiple expansion enclosures to an expansion enclosure, use reverse cabling to ensure the highest level of fault
tolerance.
The ME4 Series identifies controller modules and IOMs by enclosure ID and IOM ID. In the following figure, the controller modules are
identified as 0A and 0B, the IOMs in the first expansion enclosure are identified as 1A and 1B, and so on. Controller module 0A is connected
to IOM 1A, with a chain of connections cascading down (blue). Controller module 0B is connected to the lower IOM (9B), of the last
expansion enclosure, with connections moving in the opposite direction (green). Reverse cabling enables any expansion enclosure to fail—
or be removed—while maintaining access to other enclosures.
NOTE:
The cabling diagrams show only relevant details such as module face plate outlines and expansion ports.
Figure 13. Cabling connections between a 2U controller enclosure and 2U expansion enclosures
shows the maximum cabling configuration
for a 2U controller enclosure with 2U expansion enclosures.
18
Mount the enclosures in the rack
