IBM DS4700 manual Heat output, airflow, and cooling

are appropriate for use in a typical outlet in the destination country. See Appendix C, “Power cords,” on page 199 for more information.

Power and site wiring requirements for models with dc power supply and fan units

The storage subsystem uses wide-ranging redundant power supplies that automatically accommodate voltages to the dc power source. The dc power supplies operate within the ranges specified in Table 21 on page 27. The dc power supplies require a reliably grounded safety extra low voltage SELV source and an approved and rated disconnect device for the -48V line.

The agency rating for the DS4700 Express Storage Subsystem (dc models) is 16 amps at -42V to -60V dc. This is the overall maximum operating current for the DS4700 Express Storage Subsystem with dc power supply and fan unit CRUs.

DC power recovery: After a total dc power failure, after normal power is restored, the storage subsystem performs power-up recovery procedures automatically without operator intervention.

Power cords and receptacles: The storage subsystem ships with two dc power jumper cables used to connect to the dc power source. See “Cabling the dc power supply for dc models” on page 111 for more information.

Heat output, airflow, and cooling

See “Airflow and heat dissipation” on page 25 for heat output, airflow, and cooling specifications.

Note: In general, disk subsystem reliability tends to decrease as the ambient temperature of the environment in which it is being used increases. The ambient temperature in the immediate area of the disk enclosure unit should be kept near 22° C (72° F), or lower, to provide better reliability.

When racks that contain many storage subsystems are to be installed together, the following requirements must be met to ensure that the storage subsystems are adequately cooled:

vAir enters at the front of the rack and leaves at the back. To prevent the air that is leaving the rack from entering the intake of another piece of equipment, you must position the racks in alternate rows, back-to-back and front-to-front. This arrangement is known as “cold aisle/hot aisle” and is shown in Figure 16 on page 29.

vWhere racks are in rows, each rack must touch the rack that is next to it to reduce the amount of hot air that can flow around from the back of the rack into the intakes of the storage expansion enclosures that are in that rack. You should use Suite Attach Kits to completely seal any gaps that remain between the racks. For details about Suite Attach Kits, contact your marketing representative.

vWhere racks are in rows front-to-front or back-to-back, a gap of at least 1220 mm (48 in.) must separate the rows across the cold aisle.

vTo ensure correct airflow in each rack, the rack filler plates must be installed in unused positions. Also, all the gaps in the front of the racks must be sealed, including the gaps between the storage subsystems.

28IBM System Storage DS4700 Express Storage Subsystem: Installation, User’s and Maintenance Guide