A server group in control plane machines is different from the server groups in openstack instances. The openstack servers belongs to one server group but in OCP machines there is a different one for each machine.  shiftstack) [stack@undercloud-0 ~]$ oc get machines -A
NAMESPACE               NAME                          PHASE     TYPE     REGION      ZONE      AGE
openshift-machine-api   ostest-p72nc-master-0         Running   master   regionOne   AZhci-0   2d19h
openshift-machine-api   ostest-p72nc-master-1         Running   master   regionOne   AZhci-1   2d19h
openshift-machine-api   ostest-p72nc-master-2         Running   master   regionOne   AZhci-2   2d19h
openshift-machine-api   ostest-p72nc-worker-0-sn88p   Running   worker   regionOne   AZhci-0   2d19h
openshift-machine-api   ostest-p72nc-worker-1-zsrwg   Running   worker   regionOne   AZhci-1   2d19h
openshift-machine-api   ostest-p72nc-worker-2-llfhg   Running   worker   regionOne   AZhci-2   2d19h
(shiftstack) [stack@undercloud-0 ~]$ openstack server group list
+--------------------------------------+-----------------------------+--------------------+
| ID                                   | Name                        | Policy             |
+--------------------------------------+-----------------------------+--------------------+
| 89475f62-1ac4-44d8-9352-531327e4f002 | ostest-p72nc-worker-AZhci-1 | soft-anti-affinity |
| 2e5f94c9-5c1a-452c-842b-d4287430b931 | ostest-p72nc-worker-AZhci-0 | soft-anti-affinity |
| 48783d5e-45fb-44a7-a444-469cb3126f5c | ostest-p72nc-master-AZhci-0 | soft-anti-affinity |
| 69fcea9c-4de0-4554-afb7-da449f72aa50 | ostest-p72nc-worker-AZhci-2 | soft-anti-affinity |
+--------------------------------------+-----------------------------+--------------------+
(shiftstack) [stack@undercloud-0 ~]$ openstack server list
+--------------------------------------+-----------------------------+--------+--------------------------------------------------------------+-------+--------+
| ID                                   | Name                        | Status | Networks                                                     | Image | Flavor |
+--------------------------------------+-----------------------------+--------+--------------------------------------------------------------+-------+--------+
| e7e1f764-c247-45ef-87c0-8c5a74c86511 | ostest-p72nc-worker-0-sn88p | ACTIVE | StorageNFS=172.17.5.227; ostest-p72nc-openshift=10.196.2.225 |       | worker |
| 77e949de-bfdd-4dd1-b385-50d776879d97 | ostest-p72nc-worker-2-llfhg | ACTIVE | StorageNFS=172.17.5.171; ostest-p72nc-openshift=10.196.1.24  |       | worker |
| 0cf737f9-3590-426f-90b3-c345bdceef1d | ostest-p72nc-worker-1-zsrwg | ACTIVE | StorageNFS=172.17.5.199; ostest-p72nc-openshift=10.196.3.82  |       | worker |
| f32aa100-0831-4a52-bd1c-e9116724f6f7 | ostest-p72nc-master-2       | ACTIVE | StorageNFS=172.17.5.228; ostest-p72nc-openshift=10.196.1.40  |       | master |
| 3ed1de7e-32e9-459b-a697-9d2a8e3c8255 | ostest-p72nc-master-1       | ACTIVE | StorageNFS=172.17.5.232; ostest-p72nc-openshift=10.196.3.229 |       | master |
| 41acd674-d3f4-4456-aa24-8964e771971b | ostest-p72nc-master-0       | ACTIVE | StorageNFS=172.17.5.203; ostest-p72nc-openshift=10.196.2.201 |       | master |
+--------------------------------------+-----------------------------+--------+--------------------------------------------------------------+-------+--------+
(shiftstack) [stack@undercloud-0 ~]$ openstack server show ostest-p72nc-master-1 |grep -i group
| security_groups             | name='ostest-p72nc-master'                                                             |
| server_groups               | ['48783d5e-45fb-44a7-a444-469cb3126f5c']     
$ oc get machine ostest-p72nc-master-1 -n openshift-machine-api -o json | jq .spec.providerSpec.value.serverGroupName
"ostest-p72nc-master-AZhci-1"

    4.12.0-0.nightly-2024-07-09-174714

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