[Openstack-operators] Reducing ext4/qcow2 snapshot size

Lloyd Dewolf lloydostack at gmail.com
Tue Aug 21 16:48:15 UTC 2012

On Tue, Aug 21, 2012 at 9:47 AM, Lloyd Dewolf <lloydostack at gmail.com> wrote:
> On Mon, Aug 20, 2012 at 6:04 PM, Lorin Hochstein
> <lorin at nimbisservices.com> wrote:
>> On Aug 20, 2012, at 12:47 PM, Samuel Winchenbach <swinchen at gmail.com> wrote:
>> Hi all,
>> I launched a large (100 GB) VM and made the changes I wanted
>> (installed software, created users, etc...)  and made a snapshot.
>> Now I would like to launch VMs from that snapshot with a smaller disk
>> size, but no mater what flavor I select it always creates a 100GB
>> image.
>> Is there a way to reduce the ext4 partition size inside the qcow2 disk
>> image?   It might involve creating a new image file and cloning over
>> the original image?  If so what tools do you use for the cloning?
>> Sam:
>> You can mount the qcow2 image in your file system using qemu-nbd (see
>> http://en.wikibooks.org/wiki/QEMU/Images#Mounting_an_image_on_the_host) and
>> then resize the partition using the e2fsprogs tools (e.g., see
>> http://en.positon.org/post/Resize-an-ext3-ext4-partition).
>> I believe you can also use libguestfs <http://libguestfs.org/> as an
>> alternative to qemu-nbd, but I've never tried it.
> When last I looked qcow2 images could be shrunk, so although you can
> shrink the filesystems you won't fully benefit from the smaller size
> as the first instance will be raw'd to the full size.

Sorry, could NOT be shrunk.


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