Virtual Machine Status in OpenStack.

In OpenStack, we can see 3 types of virtual machine status:

Power status: 

Power Status is the status from hypervisor. power_state is the hypervisor state, loaded “bottom-up” from compute worker; it can be updated in DB by tasks.

There are 3 statuses: SHUTDOWN (previous  SHUTOFF)  NOSTATE (previous FAILED),  RUNNING(previous BLOCKED)

Status: 

Status (vm_status): the stable status of the VM. It should describe a VM’s current stable (not transition) state. vm_state should only be updated at the end of a task, when the task successfully finishes, and setting the task_state to None. Without API calls, the vm_state should never change.

·         INITIALIZED: VM is just created in the database, but has not been built. (was BUILDING)

·         ACTIVE: VM is running with the specified image.

·         RESCUED: VM is running with the rescue image.

·         PAUSED: VM is paused with the specified image.

·         SUSPENDED: VM is suspended with the specified image, with a valid memory snapshot.

·         STOPPED: VM is not running, and the image is on disk.

·         SOFT_DELETED: VM is no longer running on compute, but the disk image remains and can be brought back.

·         HARD_DELETED: From quota and billing’s perspective, the VM no longer exists. VM will eventually be destroyed running on compute, disk images too.

In some situation, the Power Status is not consistent with vm_status, if the VM is in transition status, that is fine. Otherwise, it usually indicate the error happened.

·         RESIZED: The VM is stopped on the source node but running on the destination node. The VM images exist at two locations (src and dest, with different sizes). The user is expected to confirm the resize or revert it. (the same functionality of the old task_state.RESIZE_VERIFY)

·         ERROR: some unrecoverable error happened. Only delete is allowed to be called on the VM.

Task Status: 

Task Status: task_state should represent a transition state, and is precisely associated with one compute API, indicating which task the VM is currently running. There are only one task (with a task id) can be running on the VM at a time. Only HARD_DELETE can pre-empt other tasks. The task status is driven by  compute API method and should not be changed during the task execution.

All the task status is named after verb-ing. There are around 20 task status in OpenStack.