OpenStack Nova provides support for resize operations, or the changing of the flavor associated with instance. This allows you to add or remove resources from the instance, in addition to modifying other configuration associated with the flavor.
There were reports that resizing an instance from a pinned flavor to a unpinned one did not result in the pinning being removed. The opposite was also reportedly true. I investigated this to see if this was the case.
Steps
Create the required flavors
The first step we’ll do is create two new flavors - test.unpinned and
test.pinned. Begin by creating these:
$ openstack flavor create test.unpinned \
--id 100 --ram 2048 --disk 0 --vcpus 2
$ openstack flavor create test.pinned \
--id 101 --ram 2048 --disk 0 --vcpus 2
$ openstack flavor set test.pinned --property "hw:cpu_policy=dedicated"
$ openstack flavor list
+-----+---------------+-------+------+-----------+-------+-----------+
| ID | Name | RAM | Disk | Ephemeral | VCPUs | Is Public |
+-----+---------------+-------+------+-----------+-------+-----------+
| 1 | m1.tiny | 512 | 1 | 0 | 1 | True |
| 101 | test.unpinned | 2048 | 0 | 0 | 2 | True |
| 101 | test.pinned | 2048 | 0 | 0 | 2 | True |
| 2 | m1.small | 2048 | 20 | 0 | 1 | True |
| 3 | m1.medium | 4096 | 40 | 0 | 2 | True |
| 4 | m1.large | 8192 | 80 | 0 | 4 | True |
| 42 | m1.nano | 64 | 0 | 0 | 1 | True |
| 5 | m1.xlarge | 16384 | 160 | 0 | 8 | True |
| 84 | m1.micro | 128 | 0 | 0 | 1 | True |
+-----+---------------+-------+------+-----------+-------+-----------+
Create a new instance
Now create the new instance, based on the test.pinned flavor:
$ openstack image list
+--------------------------------------+---------------------------------+--------+
| ID | Name | Status |
+--------------------------------------+---------------------------------+--------+
| c44bba29-653e-4ddf-963d-442af4c33a13 | cirros-0.3.4-x86_64-uec | active |
| 8b0284ee-ae6c-4e80-b5ee-26895d574717 | cirros-0.3.4-x86_64-uec-ramdisk | active |
| 855c2971-aedc-4d5f-a366-73bb14707965 | cirros-0.3.4-x86_64-uec-kernel | active |
+--------------------------------------+---------------------------------+--------+
$ openstack server create --flavor=test.pinned \
--image=cirros-0.3.4-x86_64-uec --wait test1
Validate that the instance is pinned
Ensure the instance is actually pinned in the first place before we resize anything:
$ openstack server list
+--------------------------------------+-------+--------+--------------------------------------------------------+
| ID | Name | Status | Networks |
+--------------------------------------+-------+--------+--------------------------------------------------------+
| 857597cb-266b-4032-8030-e3cc76ebf0e7 | test1 | ACTIVE | private=10.0.0.3, fd2a:ec16:99e1:0:f816:3eff:fe99:df9f |
+--------------------------------------+-------+--------+--------------------------------------------------------+
$ sudo virsh list
Id Name State
----------------------------------------------------
1 instance-00000001 running
$ sudo virsh dumpxml instance-00000001
<domain type='kvm' id='1'>
<name>instance-00000001</name>
...
<vcpu placement='static'>2</vcpu>
<cputune>
<shares>2048</shares>
<vcpupin vcpu='0' cpuset='1'/>
<vcpupin vcpu='1' cpuset='21'/>
<emulatorpin cpuset='1,21'/>
</cputune>
<numatune>
<memory mode='strict' nodeset='0'/>
<memnode cellid='0' mode='strict' nodeset='0'/>
</numatune>
...
<cpu>
<topology sockets='1' cores='1' threads='2'/>
<numa>
<cell id='0' cpus='0-1' memory='2097152' unit='KiB'/>
</numa>
</cpu>
...
</domain>
Resize the instance to the unpinned flavor
Seeing as pinning was in effect, we can now resize to the test.unpinned
flavor:
$ openstack server resize test1 --flavor test.unpinned --wait
complete
$ openstack server list
+--------------------------------------+-------+---------------+--------------------------------------------------------+
| ID | Name | Status | Networks |
+--------------------------------------+-------+---------------+--------------------------------------------------------+
| 857597cb-266b-4032-8030-e3cc76ebf0e7 | test1 | VERIFY_RESIZE | private=10.0.0.3, fd2a:ec16:99e1:0:f816:3eff:fe99:df9f |
+--------------------------------------+-------+---------------+--------------------------------------------------------+
$ openstack server resize test1 --confirm
Validate that the instance is no longer pinned
Once resized, check to see if the instance has been unpinned:
$ openstack server list
+--------------------------------------+-------+--------+--------------------------------------------------------+
| ID | Name | Status | Networks |
+--------------------------------------+-------+--------+--------------------------------------------------------+
| 857597cb-266b-4032-8030-e3cc76ebf0e7 | test1 | ACTIVE | private=10.0.0.3, fd2a:ec16:99e1:0:f816:3eff:fe99:df9f |
+--------------------------------------+-------+--------+--------------------------------------------------------+
$ sudo virsh list
Id Name State
----------------------------------------------------
2 instance-00000001 running
$ sudo virsh dumpxml instance-00000001
<domain type='kvm' id='2'>
<name>instance-00000002</name>
...
<vcpu placement='static'>2</vcpu>
<cputune>
<shares>2048</shares>
</cputune>
...
</domain>
Resize the instance back to the pinned flavor
Let’s go back the other way, and resize back to the test.pinned flavor:
$ openstack server resize test1 --flavor test.pinned --wait
complete
$ openstack server list
+--------------------------------------+-------+---------------+--------------------------------------------------------+
| ID | Name | Status | Networks |
+--------------------------------------+-------+---------------+--------------------------------------------------------+
| 857597cb-266b-4032-8030-e3cc76ebf0e7 | test1 | VERIFY_RESIZE | private=10.0.0.3, fd2a:ec16:99e1:0:f816:3eff:fe99:df9f |
+--------------------------------------+-------+---------------+--------------------------------------------------------+
$ openstack server resize test1 --confirm
Validate that the instance is pinned once more
Finally, ensure the instance is once again pinned:
$ openstack server list
+--------------------------------------+-------+--------+--------------------------------------------------------+
| ID | Name | Status | Networks |
+--------------------------------------+-------+--------+--------------------------------------------------------+
| 857597cb-266b-4032-8030-e3cc76ebf0e7 | test1 | ACTIVE | private=10.0.0.3, fd2a:ec16:99e1:0:f816:3eff:fe99:df9f |
+--------------------------------------+-------+--------+--------------------------------------------------------+
$ sudo virsh list
Id Name State
----------------------------------------------------
3 instance-00000001 running
$ sudo virsh dumpxml instance-00000001
<domain type='kvm' id='3'>
<name>instance-00000001</name>
...
<vcpu placement='static'>2</vcpu>
<cputune>
<shares>2048</shares>
<vcpupin vcpu='0' cpuset='1'/>
<vcpupin vcpu='1' cpuset='21'/>
<emulatorpin cpuset='1,21'/>
</cputune>
<numatune>
<memory mode='strict' nodeset='0'/>
<memnode cellid='0' mode='strict' nodeset='0'/>
</numatune>
...
<cpu>
<topology sockets='1' cores='1' threads='2'/>
<numa>
<cell id='0' cpus='0-1' memory='2097152' unit='KiB'/>
</numa>
</cpu>
...
</domain>
Result
It is possible to resize from pinned to unpinned, and from unpinned to pinned. No issues here.