Hi  everyone!

     I use the libvirt(version: 1.2.2) and QEMU(version: 2.2.1) to test qemu snapshot features:

    

     I tried virsh blockcommit when VM offline,  the virsh blockcommit failed: the error messase as below:

                          error: Requested operation is not valid: domain is not running

     when I start the VM,  the virsh blockcommit  work fine!

     my question is :   we need virsh support blockcommit when VM offline¡£how do£¿

    we  test qemu snapshot as follows£º

    we need  create  snapshot of the cycle£¬and  by virsh blockcommit merge snapshot chain£¬but whenVM offline£¬ the virsh blockcommit will fail£¬ someone suggest me£ºwhen VM offline£¬may use qemu-img commit to submit snapshot turn£¬but qemu-img can't modify snapshot chain backing relation£¬it need we use qemu-img  rebase amend snapshot¡®s backingfile£¬ the main question is when we use qemu-img rebase modify snapshot's backingfile, if someone start the VM, it  will may lead to VM filesystem readonly¡£

  

   we  shoule solve the question?   thanks!