IBM 990 - Manual (Page 77)

Chapter 2. System structure and design 65
Conversion of feature code 1716 to 0716, for conversion of an unassigned CP to a CP
Conversion of feature code 0516 to 0517, 0518 or 0716, for conversion of an IFL to an
unassigned IFL, an ICF, or a CP
Conversion of feature code 0517 to 0516, for conversion of an unassigned IFL to an IFL
Conversion of feature code 0518 to 0516 or 0716, for conversion of an ICF to an IFL or a
CP
All listed conversions are usually non-disruptive. In exceptional cases the conversion may be
disruptive, for example, when an IBM 2084 model A08 with eight CPs is converted to an all
IFL system. In addition, LPAR disruption may occur when PUs must be freed before they can
be converted.
This information is also summarized in Table 2-7.
Table 2-7 PU conversions
Capacity Backup (CBU)
CBUs deliver temporary capacity (feature code 7800) on top of what a customer might have
installed in numbers of assigned CPs, IFLs, ICFs, zAAPs and additional SAPs. The total
number of active PUs (the sum of all assigned CPs, IFLs, ICFs, zAAPs, and additional SAPs)
plus the number of CBUs cannot exceed the total number of PUs available on the MCMs in all
books.
To determine the number of CBUs that can be added to a given configuration, some rules
must be considered:
The number of assigned CPs + IFLs + ICFs + zAAPs + additional SAPs + CBUs equals
less than 8 on an IBM 2084-A08.
The number of assigned CPs + IFLs + ICFs + zAAPs + additional SAPs + CBUs equals
less than 16 on an IBM 2084-B16.
The number of assigned CPs + IFLs + ICFs + zAAPs + additional SAPs + CBUs equals
less than 24 on an IBM 3084-C24.
The number of assigned CPs + IFLs + ICFs + zAAPs + additional SAPs + CBUs equals
less than 32 on an IBM 3084-D32.
Unassigned CPs and IFLs are ignored. In fact, they are considered spares and are available
for use as a CBU. When an unassigned CP or IFL is converted into an assigned CP or IFL, or
when additional PUs are characterized as CPs or IFLs, then the number of CBUs that can be
activated is decreased.
To
From
CP
(0716)
Unassigned
CP (1716) IFL
(0516) Unassigned
IFL (0517) ICF
(0518)
CP (0716) - Yes Yes No Yes
Unassigned - CP (1716) Yes - No No No
IFL (0516) Yes No - Yes Yes
Unassigned IFL (0517) No No Yes - No
ICF (0518) Yes No Yes No -