Compaq 4200 Family - Manual (Page 18)

1–6 Enclosure 4200 Family LVD Disk Enclosures User Guide
Major Elements
The elements each enclosure requires for proper operation include:
■ An EMU
■ Two power supplies, or
1 power supply and 1 fan mounting assembly
■ Two Fans
■ An I/O module
■ A disk drive or disk drive blank in each bay
Element Functions
A full description of the individual elements and their functions can be found in the
individual chapters.
Element Replacement
The methods used to replace an element depend upon several factors. The primary factors
are:
■ Could element replacement affect SCSI bus operation?
When the element being replaced does not interrupt data transfer nor affect the
operation of another element, the element is “hot-pluggable.”
If replacement of the element could affect data transfers or the operation of another
element, the element replacement method is “pluggable.”
■ Are there any personal safety issues involved?
Whenever there is an issue involving personal safety, such as an electrical hazard, then
the element replacement requires quiescing the SCSI bus and removing power from the
enclosure.
Table 1–1 identifies the replacement method and type of replacement for each element.
Table 1–1 CRU Replacement Methods
Element Method
Drive Hot-pluggable
EMU Hot-pluggable