You can use the chhwres command, on the HMC, to “free up” allocated processor and memory resources from your logical partitions.
I may
want to do this if I need to improve the affinity placement of a
partition on a POWER7 system or if I need to free up resources from
trial capacity on demand in order to re-use the resources with On/Off
capacity instead.
Here’s an example of “freeing up” some processor resources from a partition.
I’d
like to remove the processor allocation from my AIX partition named
750lpar6. This partition is currently active and has 0.5 processing
units assigned to it.
hscroot@hmc1:~> lparls | grep 750lpar6
750lpar6 Running
hscroot@hmc1:~> lparlscpu | grep 750lpar6
750lpar6 0.5
I’ll stop the partition (shutdown –F) so that I may free up its processor resources. The partition is now inactive.
hscroot@hmc1:~> lparls | grep 750lpar6
750lpar6 Not Activated
Even though the partition is no longer running, the processor allocation of 0.5 cores remains assigned to this partition.
The
number of processors ‘assigned to partitions’ is 6.5 units; as shown on
the HMC GUI, under the properties of the managed system.
Now I’ll use the chhwres command to “free” the currently allocated cores from the partition.
hscroot@hmc1:~> chhwres -r proc -m 750-1 -o r --id 8 --procunits 0.5
The partition is now allocated a total of 0.0 cores and is no longer using any processor resources.
hscroot@hmc1:~> lparlscpu | grep 750lpar6
750lpar6 0.0
Looking at the managed system properties again, the number of processors ‘assigned to partitions’ has dropped to 6.0 units.
The partitions profile is NOT changed.
hscroot@hmc1:~> lparinfo 750lpar6
750lpar6
On frame 750-1
Current State: Not Activated
OS version: AIX 6.1 6100-05-01-1016
Profile properties:
Profile properties:
name=Default,lpar_name=750lpar6,lpar_id=8,lpar_env=aixlinux,all_resources=0,
min_mem=256,desired_mem=10240,max_mem=24576,min_num_huge_pages=0,desired_num_huge_pages=0,
max_num_huge_pages=0,mem_mode=ded,hpt_ratio=1:64,proc_mode=shared,min_proc_units=0.1,
desired_proc_units=0.5,max_proc_units=2.0,min_procs=1,desired_procs=4,max_procs=8,
sharing_mode=uncap,uncap_weight=128,shared
The partition is started again (activated) and it re-acquires 0.5 cores as it did prior to shut down.
hscroot@hmc1:~> lparpoweron 750lpar6
hscroot@hmc1:~> lparls | grep 750lpar6
750lpar6 Running
hscroot@hmc1:~> lparlscpu | grep 750lpar6
750lpar6 0.5