System information

140 Logical Partitions on System i5
5.1 System and partition profiles
This section discusses the concept of system and partition profiles and how they are used.
5.1.1 System profiles
A system profile is a collection of one or more partition profiles. System profiles can be used
to specify which partition profiles are activated at the same time.
5.1.2 Partition profiles
A partition profile represents a particular configuration for a logical partition. A partition profile
contains information about the resources assigned to the partition. These resources include
memory, processor processing capacity, and physical I/O slots. Partition profiles also include
information about which devices provide important partition functions (for example, load
source, console, and alternate IPL).
Each logical partition has at least one partition profile associated with it. A logical partition can
have more than one partition profile associated with it. However, only one profile can be
active at any given time. Where there are two or more partition profiles for a logical partition,
one of the profiles needs to be specified as the default partition profile. For a logical partition
with only one profile, that profile is automatically the default partition profile. The default
partition profile is used when the partition is activated if no other profile is specified.
5.1.3 Uses of partition profiles
Partition profiles provide a degree of flexibility that was not available with previous
implementations of logical partitioning.
Partition profiles can be useful when it is not possible to dynamically move resources into a
partition. For operating systems that currently do not have dynamic LPAR (DLPAR) support,
partition profiles can be used to simulate the effect of DLPAR. Moving a processor between
two partitions would involve the use of four profiles. The initial profile for partition A would be
powered off and another profile with one less processor would be started. The initial profile for
partition B would then be powered off and another profile started with one additional
processor.
A partition could have a regular profile for normal day to day operations and a second profile
for large month or quarter end processing. A development partition could also have another
profile for situations where very large compiles or builds are needed. The provider of disaster
recovery services can maintain several partition profiles for a given partition and activate one
based on which customer is coming in. A standby partition may have different profiles
representing different types of workloads that can be deployed when needed.
Note: Unlike previous versions of logical partitioning, a partition no longer owns any
resources. When a profile is activated, resources are allocated to the partition if they are
available. Partition activation may fail if certain required or critical resources are not
available or if processing resource minimums cannot be met.
Note: Activating a profile for a partition requires an IPL of that partition.