[Xen-devel] coordinating VM snapshot with LVM snapshot.

[J Nb <j_nwb@xxxxxxxxx>]

Hi
   How to co-ordinate VM snapshots and disk snapshots ? Here is a sequence I am 
thinking of automating..

  1.Tell VM to sync (say via ssh or some special agent)
     * This will do "sync" and any application specific hook to make it 
quiescent.

  2. Tell VM/Hypervisor to flush all disk buferes ?  (HOW ??? )
     * Anything at this level?

  3. Pause the VM

  4. xm save -c (To save the VMs state in to checkpoint file.)
      (This may take more time !)

  5. Take LVM snapshot for each disk. 

  6. Unpause the VM

  7. Application level resume if any.
  
  7. Use the snapshot to copy each disks ?!!!! (either dd or mount followed by 
cp/rsync)  (This can be big! Any optimization suggestions )   

  8. discard snapshot.


Would the above sequence work ? 

Any suggestions on individual steps ?

Anything specific for PV and HVM virtual machines?

Is there a backdoor to qemu-dm console ?

Does anyone know how similar functionality is implemented in XenServer product 
or Virtual Iron or anyone else? 

-nb


      


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