nova/doc/source/vmstates.rst

Virtual Machine States and Transitions

The following diagrams and tables show the required virtual machine (VM) states and task states for various commands issued by the user.

Allowed State Transitions

digraph states {

graph [pad=".35", ranksep="0.65", nodesep="0.55", concentrate=true]; node [fontsize=10 fontname="Monospace"]; edge [arrowhead="normal", arrowsize="0.8"]; label="All states are allowed to transition to DELETED and ERROR."; forcelabels=true; labelloc=bottom; labeljust=left;

/* states */ building [label="BUILDING"] active [label="ACTIVE"] paused [label="PAUSED"] suspended [label="SUSPENDED"] stopped [label="STOPPED"] rescued [label="RESCUED"] resized [label="RESIZED"] soft_deleted [label="SOFT_DELETED"] shelved [label="SHELVED"] shelved_offloaded [label="SHELVED_OFFLOADED"] deleted [label="DELETED", color="red"] error [label="ERROR", color="red"]

/* transitions [action] */ building -> active

active -> active [headport=nw, tailport=ne] // manual layout active -> soft_deleted [tailport=e] // prevent arrowhead overlap active -> suspended active -> paused [tailport=w] // prevent arrowhead overlap active -> stopped active -> shelved active -> shelved_offloaded active -> rescued active -> resized

soft_deleted -> active [headport=e] // prevent arrowhead overlap

suspended -> active suspended -> shelved suspended -> shelved_offloaded

paused -> active paused -> shelved paused -> shelved_offloaded

stopped -> active stopped -> stopped [headport=nw, tailport=ne] // manual layout stopped -> resized stopped -> rescued stopped -> shelved stopped -> shelved_offloaded

resized -> active

rescued -> active

shelved -> shelved_offloaded shelved -> active

shelved_offloaded -> active

}

Requirements for Commands

Command	Req'd VM States	Req'd Task States	Target State
pause	Active, Shutoff, Rescued	Resize Verify, unset	Paused
unpause	Paused	N/A	Active
suspend	Active, Shutoff	N/A	Suspended
resume	Suspended	N/A	Active
rescue	Active, Shutoff	Resize Verify, unset	Rescued
unrescue	Rescued	N/A	Active
set admin password	Active	N/A	Active
rebuild	Active, Shutoff	Resize Verify, unset	Active
force delete	Soft Deleted	N/A	Deleted
restore	Soft Deleted	N/A	Active
soft delete	Active, Shutoff, Error	N/A	Soft Deleted
delete	Active, Shutoff, Building, Rescued, Error	N/A	Deleted
backup	Active, Shutoff	N/A	Active, Shutoff
snapshot	Active, Shutoff	N/A	Active, Shutoff
start	Shutoff, Stopped	N/A	Active
stop	Active, Shutoff, Rescued	Resize Verify, unset	Stopped
reboot	Active, Shutoff, Rescued	Resize Verify, unset	Active
resize	Active, Shutoff	Resize Verify, unset	Resized
revert resize	Active, Shutoff	Resize Verify, unset	Active
confirm resize	Active, Shutoff	Resize Verify, unset	Active

VM states and Possible Commands

VM State	Commands
Paused	unpause
Suspended	resume
Active	set admin password, suspend, pause, rescue, rebuild, soft delete, delete, backup, snapshot, stop, reboot, resize, revert resize, confirm resize
Shutoff	suspend, pause, rescue, rebuild, soft delete, delete, backup, start, snapshot, stop, reboot, resize, revert resize, confirm resize
Rescued	unrescue, pause
Stopped	rescue, delete, start
Soft Deleted	force delete, restore
Error	soft delete, delete
Building	delete
Rescued	delete, stop, reboot

Create Instance States

The following diagram shows the sequence of VM states, task states, and power states when a new VM instance is created.

seqdiag {

edge_length = 250; span_height = 40; node_width=200; default_note_color = lightblue;

// Use note (put note on rightside) api [label="Compute.api"]; manager [label="Compute.manager"]; api -> manager [label = "create_db_entry_for_new_instance", note = "VM: Building Task: Scheduling Power: No State"]; manager -> manager [label="_start_building", note ="VM: Building Task: None"]; manager -> manager [label="_allocate_network", note ="VM: Building Task: Networking"]; manager -> manager [label="_prep_block_device", note ="VM: Building Task: Block_Device_Mapping"]; manager -> manager [label="_spawn", note ="VM: Building Task: Spawning"]; api <-- manager [note ="VM: Active Task: None"];

}