Connecting the optional 2U SAS expansion enclosures
After you install the SAS expansion enclosures into the rack, you
must connect them to each node in the IO group that will use them.
About this task
This task applies if you are installing a 2145-24F or 2145-12F
expansion enclosure. Each pair of 2145-SV1 nodes in the system
can manage up to 20 expansion enclosures.
Note: When you insert SAS cables, ensure that the connector is oriented correctly.
When you connect an expansion enclosure, the blue pull tab must be below the cable
( 1 in Figure 1).
When you connect a 2145-SV1, 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.
Figure 1. SAS cable connector orientation
1 Correct orientation for 2145-24F or 2145-12F SAS expansion enclosure
2 Correct orientation for 2145-SV1 node or 2145-92F SAS expansion enclosure
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 avoid the risk of disconnecting
the nodes from their flash drive arrays. This step also helps to protect the SAS cables from getting
damaged if the node is slid out on its rails while attached to the enclosure.
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. USB ports can be used to initialize the system or to perform service-related tasks by
using a USB flash drive that contains executable files for initializing the system.
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 the following figure. Note: this illustration is provided to
show the cable connections between the SAS enclosures and each 2145-SV1. It does not imply or
represent the precise racking order for the devices in a cabinet/rack.
Figure 2. Connecting the SAS cables
1 2145-24F or 2145-12F SAS expansion
enclosure
2 2145-24F or 2145-12F SAS expansion
enclosure
3 2145-SV1 with SAS adapter in
PCIe expansion slot 2
4 2145-SV1 with SAS adapter in
PCIe expansion slot 2
5 2145-24F or 2145-12F SAS expansion
enclosure
6 2145-24F or 2145-12F SAS expansion
enclosure
If more I/O groups are configured, repeat the cabling procedure for the other I/O groups. The
system supports up to four I/O groups with a total of 80 expansion enclosures per system.
Combining 2U and 5U expansion enclosures
About this task
You can combine 2145-24F, 2145-12F, and 2145-92F enclosures in an 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:
2145-92F enclosures have a
chain weight of 2.5
2145-24F and 2145-12F enclosures have a chain
weight of 1.
Example
Table 1. Examples of supported SAS chain combinations
