Connecting optional 5U expansion enclosures

After you install 5U expansion enclosures into the rack, you must connect them to each system that will use them. The system requires software version 7.8.0 or later. Do not connect the expansion enclosure if software version 7.8.0 is not installed on the system.

About this task

This task applies if you are installing a 5U expansion enclosure.

Note: When you insert SAS cables, ensure that the connector is oriented correctly to the control enclosure and expansion enclosure.

For Storwize® V7000 Gen2 systems, Storwize V7000 Gen2+ control enclosures, and 2U expansion enclosures, the blue pull tab must be below the cable ( 1 in Figure 1).
Figure 1. SAS cable connector orientation
For 2076-92F 5U expansion enclosures, the blue pull tab must be above the connector ( 2 in Figure 1).
Insert the connector gently until it clicks into place. If you feel resistance, the connector is probably oriented the wrong way. Do not force it.
When inserted correctly, the connector can be removed only by pulling the tab.

Be aware of the following guidelines when you attach the cables to the SAS ports.

No cable can be connected between a port on a left canister and a port on a right canister of the expansion enclosures.
Ensure that cables are installed in an orderly way to reduce the risk of cable damage when replaceable units are removed or inserted.
SAS cables must be routed through the cable management arms to reduce the risk of disconnecting the nodes from their storage arrays. This step also helps to protect the SAS cables from getting damaged if you slide the node or enclosure out of the rack while they are attached. Arrange your cables to provide access to the following components:
- Ethernet ports, including the technician port. The technician port is used for initial setup of the system by directly attaching to a personal computer. It can also be used to complete service actions for the system.
- USB ports.
- Fibre Channel and Fibre Channel over Ethernet (FCoE) ports. If your system has an optionally installed Fibre Channel and FCoE adapter for host and external storage attachment, ensure that these ports are accessible.
- The nodes and the enclosures themselves. Access is required to the hardware for servicing and for safely removing and replacing components by using two or more people.

Procedure

Install the cables, as shown in Figure 2.

Note: Figure 2 shows the cable connections between the SAS enclosures and the control enclosure. It does not imply or represent the precise racking order for the enclosures in a rack. However, due to its size and weight, always place the 5U enclosure near the bottom of the rack.

Figure 2. Connecting the SAS cables
If more I/O groups are configured, repeat the cabling procedure for the other I/O groups. Each system can have a maximum of four I/O groups, with two chains of expansion enclosures attached to each I/O group. Two chains of expansion enclosures can be attached to each I/O group. On each SAS chain, the systems can support up to a SAS chain weight of 10.

Combining 2U and 5U expansion enclosures

About this task

As Figure 2 shows, you can combine 2U expansion enclosure (12 and 24 drive models) and 5U enclosures in a SAS chain. The limiting factor is the combined chain weight of the various components. The maximum SAS chain weight that can be attached to a node SAS port is 10:

5U expansion enclosures have a chain weight of 2.5
2U expansion enclosures have a chain weight of 1.

Example

Table 1 shows example of different combinations of SAS weights.

Table 1. Examples of supported SAS chain combinations
2U Enclosures (12 drives)	2U Enclosures (24 drives)	5U Enclosures (92 drives)	Combined chain weight
2	0	3	9.5
2	3	2	10
0	7	1	9.5
1	1	1	4.5 (as shown in Figure 2)

In addition, the orientation of the Input and Output SAS ports on the 2U and 5U SAS enclosures differs. Figure 3 shows the SAS ports on the 5U and 2U expansion enclosures.

Figure 3. SAS port orientation on expansion enclosures

1 Input SAS port
2 Output SAS port