Requirements for Redundant Power

If a DC supply in a PCM fails, the system boards will continue to be powered and cooled by the other power supplies if sufficient redundancy (an additional power supply) is present.

For example, if an Enterprise system needs a minimum of three power supplies and four are present, then the system has redundancy. However, fully configured Enterprise systems represent a different situation and are always hot-pluggable. That is, an Enterprise 5500 or 4500 system with seven or eight boards and four PCMs is hot-pluggable. (The peripheral power supply acts as the "extra" power supply.) Similarly, an Enterprise 6500 system with fifteen or sixteen boards and eight power supplies is also hot-pluggable. (Seven PCMs are sufficient to power sixteen active boards; the eighth PCM is "extra." However, the eighth PCM is required for cooling purposes.) See Table 7-3.

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Note -

The presence of an additional (extra) PCM in the system provides redundancy and allows hot-plug of PCMs.

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Table 7-3 Minimum and Redundant Working Power Supplies Required to Power Active Boards

	Enterprise 5500/4500 Systems		Enterprise 6500 System
Number of Boards	Minimum Working Power Supplies	Redundant Working Power Supplies (Hot-pluggable)	Minimum Working Power Supplies	Redundant Working Power Supplies (Hot-pluggable)
1-2	1	2	1	2
3-4	2	3	2	3
5-6	3	4	3	4
7-8	3 + peripheral supply*	4 + peripheral supply	4	5
*Note: System needs a fourth PCM for cooling purposes
9-10			5	6
11-12			6	7
13-14			7	8
15-16			7*	8
		*Note: System needs an eighth PCM for cooling purposes

Failed power supplies must be replaced as soon as practical. Operating an Enterprise system without a redundant power supply will result in an outage at the next PCM failure.