[CentOS-devel] Cloud and VM Images
Richard W.M. Jones
rjones at redhat.com
Sat Jun 21 08:45:27 UTC 2014
On Sat, Jun 21, 2014 at 03:10:39AM +0100, Karanbir Singh wrote:
> hi,
>
> I have just pushed a public build for a qcow2 image, this should be
> suiteable for any HVM environment. Please test as widely as possible.
>
> http://buildlogs.centos.org/centos/7/cloud/
Is that built using the centos.sh script?
As a general comment, although not required, virt-builder would prefer
it if the image was xz-compressed. The reason is that it has to
download the template and cache it in the user's $HOME, so a 960MB
template is obviously both slow to download and takes a lot of space.
NB: Don't bother with qcow2's internal compression feature. It's a
waste of space. xz is where it's at.
- nearly best in class compression
- real API (liblzma)
- preserves sparseness, important for raw format images
- virt-builder has a custom multithreaded unxz [1] -- it is
sysconf(_SC_NPROCESSORS_ONLN) times faster than unxz
Rich.
[1] https://github.com/libguestfs/libguestfs/blob/master/builder/pxzcat-c.c
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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