title: OpenStack VM File System Error on reboot and nova rescue Cannot rescue a volume-backed instance (HTTP 400)
body: <p>Openstack VM's File system went into read-only mode and rebooted it. After the reboot I'm getting grub menu and auto booting from the Kernel and seeing only blank screen in Openstck dashboard console.</p>
  
  <p>I tried nova rescue but failed with below error,</p>
  
  <p><code>cannot be rescued: Cannot rescue a volume-backed instance (HTTP 400)</code></p>
  
  <p>I did edited the grub and enetered single/rescue mode to fix the file system error but still I'm getting blank screen after <code>ctrl+x</code> in grub edit.
  I want to bring up the vm instance and how do I fix the file system error.</p>
  
  <p>File system error happened as of vm's backend storage, ceph sds node's all went down as of power failure and restored back.</p>
  
  <p>I'm using RHOSP 13 and VM's image is RHEL 7.</p>