openstack team mailing list archive

[Gaurab Basu <basugaurab88@xxxxxxxxx>]

Hi Jay,

Thanks a lot again, trying to get an understanding of the overall process.

So the file system for qcow2 is sort of managed by qemu(not by openstack
itself) ... create etc is done by qemu but read/write from filesystem is
also manged by qemu?
Is the filesystem supported by qemu for all cases(hypervisors other than
kvm, or different image formats or when COW layer is not implemented)
or does openstack have it's own filesystem management as well.

And my next question is regarding memory management. In memory blocks are
read/write to and from filesystem.
So this process is supported by openstack ( if so,where should i look in
the code for memory management ) or qemu?

Thanks and Regards,
Gaurab

On Thu, Aug 2, 2012 at 10:53 PM, Jay Pipes <jaypipes@xxxxxxxxx> wrote:

> On 08/02/2012 07:47 AM, Gaurab Basu wrote:
> > Hi Jay,
> >
> > Thanks for your reply, it helped me get started.
> >
> > I have been going through the code and some of the sparse docs that are
> > available.
> >
> > This is the code file
> > https://github.com/openstack/nova/blob/master/nova/virt/libvirt/utils.py
> >
> > However I am facing a new issue and require some help. I wanted to
> > modify how openstack handles the cow layer as such and also the qcow2
> > format.
> > It turns out that openstack issues the external command "qemu-img".
> >
> > First of all, is qemu-img internal to openstack ( I mean code for how
> > qemu-img is implemented is in openstack or in qemu )
> > It is in openstack, where is the code located.
> >
> > If it is outside openstack, does that mean i have to change the code in
> > qemu and then link those binaries with openstack.
>
> QEMU is a totally separate project from Nova, yes. QEMU is written in C
> and has a number of executables such as qemu-img and qemu-nbd, etc. Nova
> calls out to these executables in subprocesses.
>
> If you want to make changes to QEMU, yes, you would want to look into
> the QEMU contribution process and community.
>
> Here's where to start:
>
> http://wiki.qemu.org/Documentation/GettingStartedDevelopers
>
> Best,
> -jay
>