openstack team mailing list archive

[<masumotok@xxxxxxxxxxxxx>]

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@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@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