This is a guide to using SAS cables to connect 2U and 5U expansion enclosures in a rack
to the control enclosure in the rack.
About this task
This task applies if you are installing one or more expansion enclosures.
Note: It is recommended that you read the following "SAS Cabling Guidelines" before you connect any
SAS cables between the control enclosure and any expansion enclosures in the rack.
SAS cabling guidelines
Orienting the connector
When
you insert SAS cables, make sure the connector (Figure 1) is oriented
correctly.
The orientation of the connector must match the orientation of the port before you push the
connector into the port. The cable connector and socket are keyed, and it is important that you have
proper alignment of the keys when the cable is inserted.
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.
When both ends of a SAS cable are inserted correctly, the green link LEDs next to the connected
SAS ports are lit.
For FlashSystem control enclosure node canisters and 2U expansion enclosures, the blue pull tab
must be below the cable ( 1 in Figure 1).Figure 1. SAS cable connector orientation
For 5U expansion enclosure canisters, 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. See Figure 2.Figure 2. Pushing the SAS cable latch closed
When inserted correctly, the connector can be removed only by pulling the tab.
Guidelines
Be aware of the following guidelines when you connect the SAS ports of a control enclosure
canister to the SAS ports of a 2U and 5U expansion enclosure canister.
The FlashSystem models support 4-port SAS interface adapters. However, only ports 1 and 3 are
used for SAS connections, as Figure 3 shows.
See Enclosure location guidelines for the number and type
of expansion enclosures that can be chained to SAS port 1 and SAS port 3 of a node canister. The
expansion enclosures in this chain must be installed below the control enclosure (as shown in Figure 3).
Do not connect a cable between a SAS port on a left canister and a SAS port on a right
canister.
Do not connect a cable between SAS ports in the same enclosure.
Do not connect a SAS port on a control canister to more than one SAS port on an expansion
canister. Cables that split the SAS connection out into separate physical connections are not
supported.
Attach cables serially between enclosures; do not skip an enclosure.
It is recommended that SAS cables 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.
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.
Do not place any cables in SAS port 2 of canister 1 or SAS port 2 of canister 2, of the last
expansion enclosure in a chain.
Ensure that cables are installed in an orderly way to reduce the risk of
cable damage when replaceable units are removed or inserted.
Note:
Figure 3 shows an example
configuration of a control enclosure that is connected to two SAS chains.
Each chain consists of a 2U expansion enclosure and a 5U high-density expansion enclosure.
Figure 3 is a generic
cabling diagram intended to illustrate how to cable the different types of expansion enclosure. Some
systems do not allow for a mixture of expansion enclosure types in the same chain. See Expansion enclosures for details on the supported expansion
enclosures for your specific system model.
The order of the SAS ports on the 5U high-density expansion enclosure differs from the order of
the SAS ports of a 2U expansion enclosure because the canisters in the 5U expansion enclosure are
rotated.
Procedure
Using the supplied SAS cables, connect the control enclosure to the expansion enclosure at rack
position 1, as shown in Figure 3.
Connect SAS port 1 of the uppermost or leftmost node canister in the control enclosure to SAS
port 1 of the left expansion canister in the first expansion enclosure.
Connect SAS port 1 of the lowermost or rightmost node canister in the control enclosure to SAS
port 1 of the right expansion canister in the first expansion enclosure.
To add further expansion enclosures, continue to connect the expansion canisters as shown in
Figure 3.
Figure 3. Connecting the SAS cables to control enclosure
