Best practices for integrating cable and system placement

These guidelines ensure that your system and its cables have optimal clearance for maintenance and other operations. The guidelines also provide guidance in correctly cabling your system and using the appropriate cables.

The following guidelines provide cabling information for installing, migrating, relocating, or upgrading your system:

• Position drawers in racks to allow enough space, where possible, for cable routing on the bottom and top of the rack, and between drawers.
• Shorter drawers should not be placed between longer drawers in the rack (for example, placing a 19-inch drawer between two 24-inch drawers).
• When a specific cable plugging sequence is required, for example, for concurrent maintenance (symmetric multiprocessing cables), label the cables appropriately and note the sequence order.
• To facilitate cable routing, install cables in the following order:
  1. System power control network (SPCN) cables
  2. Power cables
  3. Communications (serial attached SCSI, InfiniBand, remote input/output, and peripheral component interconnect express) cables
     Note: Install and route the communications cables, starting with the smallest diameter first and then progressing to the largest diameter. This applies to installing them into the cable management arm and retaining them to the rack, brackets, and other features that may be provided for cable management.
• Install and route the communications cables, starting with smallest diameter first and then progressing to the largest diameter.
• Use the innermost cable-management bridge lances for SPCN cables.
• Use the middle cable-management bridge lances for power and communications cables.
• The outermost row of cable-management bridge lances are available for use when routing cables.
• Use the cable raceways on the sides of the rack to manage excess SPCN and power cables.
• There are four cable-management bridge lances on the top of the rack. Use these bridge lances to route the cables from one side of the rack to the other, by routing to the top of the rack, where possible. This routing helps to avoid having a cable bundle that blocks the cable exit opening at the bottom of the rack.
• Use the cable management brackets provided with the system to maintain concurrent maintenance routing.
• Maintain a minimum bend diameter of 101.6 mm (4 in.) for communications (SAS, IB, RIO, and PCIe) cables.
• Maintain a minimum bend diameter of 50.8 mm (2 in.) for power cables.
• Maintain a minimum bend diameter of 25.4 mm (1 in.) for SPCN cables.
• Use the shortest-length cable available for each point-to-point connection.
• If cables have to be routed across the rear of a drawer, leave enough slack to reduce the tension on the cables for maintenance of the drawer.
• When routing cables, leave enough slack around the power connection on the power distribution unit (PDU) so that the wall-to-PDU line cord can be attached to the PDU.
• Use hook-and-loop fasteners where necessary.

Figure 1. Cable management bridge lances

Figure 2. Cable bend radius