Pause, suspend, and restore

Free guest CPUs or host RAM without losing a persistent lab.

Pause vs suspend

Command	Process	Host RAM	Status	Resume with
`grain pause`	QEMU stays up	Still held	`paused`	`grain resume`
`grain suspend`	QEMU stopped	Freed	`suspended`	`grain restore`
`grain stop`	Stopped	Freed	ephemeral deleted / persistent `stopped`	`grain start`

Pause freezes vCPUs via QMP (stop / cont). Use it for a short break without tearing down networking.

Suspend is for persistent VMs only. grain attempts a qcow2 savevm snapshot when possible, then stops the process. Restore loads the snapshot if present, otherwise cold-boots the disk.

grain new -p -n lab
# ... work ...
grain suspend lab
# hours later
grain restore lab

Rules of thumb

Ephemeral VMs: prefer rm or stop (they are disposable)
Persistent labs: suspend / restore or stop / start
start rejects a suspended VM — use restore
Suspended VMs do not count toward running resource caps

API

POST /vms/{name}/pause
POST /vms/{name}/resume
POST /vms/{name}/suspend
POST /vms/{name}/restore