Re: [Libguestfs] [libvirt-users] virt-sparsify changing the apparent-size of files
On Thu, 23 Jun 2016 17:57:53 +0100
"Richard W.M. Jones" <rjones(a)redhat.com> wrote:
On Thu, Jun 23, 2016 at 10:57:43AM -0500,
libvirt_users(a)skagitattic.com wrote:
> Thanks for all the information, I think my last remaining question
> is why the image created with virt-install shows the full apparent
> size and the image from virt-sparsify does not? (The image
> testimage1.qcow2 created with default options).
I don't really know what you mean by "full apparent size". If you are
talking about the output of "ls -l", then don't -- that number is
unrelated to the virtual size or the space consumed on disk. Always
use "qemu-img info".
So I think I figured out what's different. If I do
preallocation=metadata I end up with the apparent size the same as the
initial install.
# virt-sparsify testimage.qcow2 testimage3.qcow2 --tmp /bigtmp -o
preallocation=metadata Input disk virtual size = 53687091200 bytes
(50.0G) Create overlay file in /bigtmp to protect source disk ...
Examine source disk ...
Fill free space in /dev/sda1 with zero ...
100%
00:00 Clearing Linux swap on /dev/sda5 ... Copy to destination and
make sparse ...
Sparsify operation completed with no errors. Before deleting the
old disk, carefully check that the target disk boots and works
correctly.
# ls -lsh testimage.qcow2 testimage1.qcow2 testimage3.qcow2
1.1G -rw-r--r-- 1 root root 1.1G Jun 22 22:41 testimage1.qcow2
1.1G -rw-r--r-- 1 root root 51G Jun 23 16:20 testimage3.qcow2
2.5G -rw-r--r-- 1 root root 51G Jun 22 20:22 testimage.qcow2
I don't know how to tell what the image's pre-allocated state is other
then checking for apparent size as "qemu-img info" does not see a
difference (other then the fact I played around with snapshotting on
the testimage1).
# qemu-img info testimage1.qcow2
image: testimage1.qcow2
file format: qcow2
virtual size: 50G (53687091200 bytes)
disk size: 1.1G
cluster_size: 65536
Snapshot list:
ID TAG VM SIZE DATE VM
CLOCK 1 test 0 2016-06-22 22:41:44
00:00:00.000 Format specific information:
compat: 1.1
lazy refcounts: false
# qemu-img info
testimage3.qcow2 image: testimage3.qcow2
file format: qcow2
virtual size: 50G (53687091200 bytes)
disk size: 1.0G
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
I will read up some more on preallocation though and hopefully find all
the answers I need.
Thanks for your help looking at this,
Keelan
Rich.