IBM 4957-J11, Hardware Installation And Maintenance Manual

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Figure 16. LEDs - system fan module - rear panel
Table 9. LEDs - system fan module - rear panel
Module LED
LED behavior states
System Fan Status LED System Fan OK (Off) Fan fault/ID (amber/
blinking amber)
Power off (Off)
Multiple system fan modules
The Disk Enclosure includes four system fan CRUs which provide redundant cooling for the system, so
that if one module fails, the others maintain airflow circulation, and enclosure operation is not affected
while you replace the faulty module. Within this CRU module, if one of the two internal rotors fails, then a
fault occurs, indicating module failure. A dual rotor failure is reported as a dual-fault.
System fans are hot-pluggable, and replacement should only take a few seconds. Replacement must be
completed as soon as possible after the removal of the defective system fan to avoid a thermal exception.
The replacement procedure should be completed within an absolute maximum of 2 minutes for this CRU
module.
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 system fans prior to powering on the
enclosure.
System airflow
The system must be operated with low pressure rear exhaust installation. Back pressure created by rack
doors and obstaclesis not to exceed 5 pascals (0.5mm water gauge). The cooling system provides
sufficient capacity to ensure that maximum temperatures are not exceeded.
Important:
18 IBM Cloud Object Storage System: Medium/Large J11/J12 Disk Enclosure Hardware Installation and
Maintenance Manual