[Openstack] snapshot question
masumotok at nttdata.co.jp
masumotok at nttdata.co.jp
Wed Jun 22 04:55:52 UTC 2011
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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