IBM Medium J11, Hardware Installation And Maintenance Manual

Page: 37 / 104

Figure 15. LEDs - 2000W PSU - rear panel
Table 8. LEDs - 2000W PSU - rear panel
Module LED
LED behavior states
PSU Status LED (Bitonal) PCM OK (Green) PSU fault/failure
(Amber/blinking amber)
Power off (Off)
Multiple power supply unit modules
The 4U storage system includes two PSUs which provide redundant power control for the system so that
if one module fails, the other maintains the power supply, and enclosure operation is not affected while
you replace the faulty module.
PSUs are hot-pluggable, and replacement should only take a few seconds to do. Replacement must be
completed as soon as possible after the removal of the defective PSU to avoid a thermal exception. The
replacement procedure should be completed within an absolute maximum of three minutes.
Important:
Operation of the enclosure with any modules missing will disrupt the airflow, and the disks will not
receive sufficient cooling. It is essential that all slots are fitted with PSUs prior to powering on the
enclosure.
System fan module
Enclosure cooling is provided by four system fan modules used in combination with two controller
channel fan modules. The IOM provides fan and LED control. This section describes system fan modules.
See also the “Controller channel fan module” on page 22 section.
Chapter 3. System overview 17