Waiting for your reply, thank you very much!
On Tue, Oct 13, 2015 at 10:39:58AM +0800, justlibvirt gmail com wrote:> Hi everyone!Hi,Firstly, please don't post the same message multiple times in a row. Ifsomeone hasn't responded, they're either busy, or haven't noticed thismessage.> 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？As near as I know, 'blockcommit' hasn't yet gotten offline support.> we test qemu snapshot as follows： we need create snapshot of> the cycle，and by virsh blockcommit merge snapshot chain，but> when VM 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，As you note there's the 'qemu-img commit' primitive that allows you tocommit the changes in an overlay back into its base image:If you have: base.qcow2 <-- overlay1.qcow2 <-- overlay2.qcow2And, if you do:$ qemu-img commit overlay2.qcow2It'll commit the contents of overlay2.qcow2 into overlay1.qcow2.And, indeed use the 'qemu-img rebase' to modify the backing file is theonly method I know of, for offline operations.> 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。Though I haven't tested this recently, why would it lead to VMfilesystem becoming read-only?> we should how to solve the question? thanks! >--/kashyap