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6 - Airflow label
7 - Captive screw
The SAN256B-6 has two power supplies installed. Use of the high-voltage line (200 to 240 VAC) is highly
recommended because of better power conversion efficiency. Refer to "Power Supply Requirements" in
Appendix B, "Product Specifications," on page 231 for minimum power supplies required for AC low and
high voltage line operation, redundancy in case of power supply failure, and other specifications.
Redundant AC primary power connections ensure high availability. Each power supply has its own
connector, so two primary power connections are required for the SAN256B-6 for optimum efficiency and
redundancy.
Power supplies can be removed and replaced without special tools. If replacing one power supply, the
device can continue operating during replacement if procedures are followed in this guide.
Power cords for these power supplies that meet your site and country requirements are available from
IBM.
Fan and power supply airflow
All fans and power supply FRUs installed in this device must have either NPI (nonport-side intake) or
NPE (nonport-side exhaust) airflow. You must order a replacement FRU with the same part number
(P/N) as the FRU being replaced to provide the same airflow. The manufacturing P/N, located on the
top of the FRU, contains either NPI or NPE. If a mismatched power source or fan assembly is installed by
mistake, a RASlog message occurs indicating that a mismatch in fan or power supply airflow has
occurred and the FRU is faulted.
Note: If airflow direction for a power supply assembly does not match the chassis airflow direction as
stored on WWN cards, the power supply will have a "fault" status. However, LED operation for the
power supply will not indicate a fault. If airflow direction for a fan assembly does not match the chassis
airflow direction, the fan LED will indicate a fault condition.
You can use external labels as a guide. The power supply and fan assemblies are labeled with a green "E"
or orange "I" airflow symbol on the faceplate. The symbol also appears on the top of the FRU. All fans
and power supplies in a chassis must have the same label affixed to guarantee airflow direction is
consistent.
Figure 66. Airflow labels
The orange I symbol indicates an intake FRU. This unit pulls air in from the nonport side of the device
and exhausts it out the port side. This is called back-to-front airflow or intake airflow. This symbol
should appear on FRUs with part numbers that contain an NPI.
The green E symbol indicates an exhaust FRU. This unit pulls air in from the port side of the device and
exhausts it out the nonport side. This is called front-to-back airflow or exhaust airflow. This symbol
should appear on FRUs with part numbers that contain an NPE.
Ensure airflow direction of power supply and fan assemblies match airflow direction of the chassis
configured on installed WWN cards. If power supply or fan air flow direction does not match, the FRU
will fault. Faulty fans can cause increase in temperature.
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SAN256B-6 Installation, Service, and User Guide
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