System information

18 Logical Partitions on System i5
Configuring the virtual processors setting is similar to telling the logical partition how many
processors it can run jobs on simultaneously. Figure 1-13 shows an illustration of the Virtual
Processor configuration. The figure shows the difference of the implementation of virtual
processor configuration of one shared logical partition with 2 virtual processors and with 4
virtual processors. There are 4 processors available in the shared processors pool. The
logical partition is assigned 1.6 processing units out of 4 processing units from the shared
processors pool.
Please note that creating many virtual processors may slow down your logical partition
operation. Please calculate the proper number of virtual processors for your logical partition.
Click OK to save changes.
Figure 1-13 A logical partition with two and four virtual processors
When you activate the logical partition using a partition profile with a shared processor, the
desired number of virtual processors will be assigned to the logical partition. Based on the
configuration in Figure 1-12 on page 17, the logical partition will have 2 virtual processors
available to support its workload.
You may increase the number of processing units and virtual processors for a logical partition
using Dynamic Logical Partitioning (DLPAR).
For example, suppose your current logical partition processor setting is similar to the setting
in Figure 1-14. Then if you want to add 2 additional virtual processors to this logical partition,
you can use Dynamic Logical Partitioning to add processing units:
Selected → Dynamic Logical Partitioning → Processor Resources → Add
P 1
P 2
8 ms
P 1
P 2
P 3
4 ms
Logical partition with 1.6 processing units and 2 virtual processors
P 4
8 ms
4 ms
4 ms
P 3
P 4
4 ms
Logical partition with 1.6 processing units and 4 virtual processors
P 1
P 2
8 ms
P 1
P 2
P 3
4 ms
Logical partition with 1.6 processing units and 2 virtual processorsLogical partition with 1.6 processing units and 2 virtual processors
P 4
8 ms
4 ms
4 ms
P 3
P 4
4 ms
Logical partition with 1.6 processing units and 4 virtual processorsLogical partition with 1.6 processing units and 4 virtual processors