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：

    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：when 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  should how to  solve the question?   thanks!