bhouse-nexthop opened a new issue, #14645:
URL: https://github.com/apache/cloudstack/issues/14645

   ### problem
   
   A size-only `resizeVolume` of a running system VM's volume, for example a 
virtual router's ROOT, is accepted and resizes the volume on the storage. The 
running system VM is never told, so the guest keeps seeing the old size until 
it next starts. The API, the database and the storage all report the new size 
while the VM still runs on the old one.
   
   `VolumeApiServiceImpl.orchestrateResizeVolume` only looks the VM up as a 
user VM (`_userVmDao.findById`). For a system VM that returns null, so the 
resize is sent with the instance name `none` and no host. On KVM the image is 
grown, but `virsh blockresize` is never run for the running domain. The 
per-hypervisor checks in the same method (XenServer can only resize a stopped 
VM's disk; on KVM the VM's host must be Up and Enabled) are skipped for the 
same reason.
   
   Other paths already treat system VM volumes differently:
   - volume snapshots of system VM volumes are refused;
   - attach and detach accept only user VMs;
   - a ROOT resize through a new disk offering is refused unless the VM is 
Stopped.
   
   The size-only path has no such check.
   
   ### versions
   
   4.22, and main.
   
   ### The steps to reproduce the bug
   
   Seen on KVM with Ceph RBD primary storage:
   1. Take a running virtual router whose ROOT disk offering is not size-strict.
   2. Call `resizeVolume id=<router ROOT volume> size=<larger size in GB>`.
   3. The call succeeds. `listVolumes` and `rbd info` show the new size.
   4. On the host, `virsh domblkinfo <router> vda` still shows the old size, 
and so does `lsblk` in the router. The new size only appears after the router 
is restarted.
   
   ### What to do about it?
   
   Refuse to resize the volume of a system VM that is not Stopped, with an 
error telling the admin to stop it first. Resizing it while it is stopped keeps 
working as before, and the VM sees the new size when it starts.
   
   Doing the resize live instead would mean running the system VM's resize 
through the VM work queue and notifying the hypervisor, as is done for user 
VMs, and checking that on each hypervisor. Refusing is the smaller, safer 
change.
   


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