首先看一下虚拟机有多少种状态：(/nova/compute/vmstates.py)

1 ACTIVE = 'active'  # VM is running 2 BUILDING = 'building'  # VM only exists in DB 3 PAUSED = 'paused' 4 SUSPENDED = 'suspended'  # VM is suspended to disk. 5 STOPPED = 'stopped'  # VM is powered off, the disk image is still there. 6 RESCUED = 'rescued'  # A rescue image is running with the original VM image 7 # attached. 8 RESIZED = 'resized'  # a VM with the new size is active. The user is expected 9 # to manually confirm or revert.10 11 SOFT_DELETED = 'soft-delete'  # VM is marked as deleted but the disk images are12 # still available to restore.13 DELETED = 'deleted'  # VM is permanently deleted.14 15 ERROR = 'error'16 17 SHELVED = 'shelved'  # VM is powered off, resources still on hypervisor18 SHELVED_OFFLOADED = 'shelved_offloaded'  # VM and associated resources are19 # not on hypervisor20 21 ALLOW_SOFT_REBOOT = [ACTIVE]  # states we can soft reboot from22 ALLOW_HARD_REBOOT = ALLOW_SOFT_REBOOT + [STOPPED, PAUSED, SUSPENDED, ERROR]23 # states we allow hard reboot from24 25 ALLOW_TRIGGER_CRASH_DUMP = [ACTIVE, PAUSED, RESCUED, RESIZED, ERROR]26 # states we allow to trigger crash dump27 28 ALLOW_RESOURCE_REMOVAL = [DELETED, SHELVED_OFFLOADED]29 # states we allow resources to be freed in

 

在删除虚拟机时，会根据虚拟机状态来进行不同的操作。可以看出deleted和shelved_offloaded两种状态下虚拟机资源完全释放，而shelved