Open Stack

Ping. I think Kei's suggestion below is a good one... can someone
knowledgeable with qemu respond?

-jay

On Tue, Jun 21, 2011 at 9:55 PM,  <masumotok at nttdata.co.jp> wrote:
> Hello,
>
> I have a question about nova.virt.libvirt.connection.snapshot().
> In my understandings, this method is currently used for saving(cloning) VM images and upload cloned image to Glance.
>
> Q1) Is there any reason why method name is snapshot() , not image_create or image_save or something?
> I am just wondering if there will be additional work to add VMWare-like snapshotting(meaning taking snapshot many times, user can select one of them, and VM state can get back...)
>
> Q2) In current implementation original disk size is bigger after nova image-create. Please see below.
>
> [before image-create]
> root at testhost:/opt/openstack/instances/instance-00000015# ls -l
> total 151580
> -rw-r----- 1 libvirt-qemu kvm       2889 2011-06-23 11:53 console.log
> -rw-r--r-- 1 libvirt-qemu kvm  155189248 2011-06-23 11:56 disk
> -rw-r--r-- 1 libvirt-qemu kvm    6291968 2011-06-23 11:50 disk.local
> -rw-r--r-- 1 root         root      1728 2011-06-23 11:49 libvirt.xml
>
> [after image-create]
> root at testhost:/opt/openstack/instances/instance-00000015# ls -l
> total 3734664
> -rw-r----- 1 libvirt-qemu kvm        2889 2011-06-23 11:53 console.log
> -rw-r--r-- 1 libvirt-qemu kvm   603979776 2011-06-23 13:02 disk
> -rw-r--r-- 1 root         root     197120 2011-06-23 12:11 disk.diff
> -rw-r--r-- 1 libvirt-qemu kvm    10486272 2011-06-23 12:59 disk.local
> -rw-r--r-- 1 root         root       1728 2011-06-23 11:49 libvirt.xml
>
> That means if any sensitive users do "nova-image create", compute node original image size is bigger and compute node disk size available is decreasing. So I would like to ask, the below operation is inappropriate here?
> a) taking diff backup: qemu-img create -b disk -f qcow2 disk.diff
> b) convert : qemu-img convert -f -O qcow2 disk.diff new_img
>
> Disk size is not bigger this way. In addition, if --use_cow_image=False, this way can be used.
> Any opinion on this? If I misunderstand somehow, please let me know.
>
> Regards,
> Kei
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