Hi Gaurab, Openstack is not a hypervisor, it is a management layer that sits on top of a hypervisor. Management of the guest filesystem and memory is all done by an underlying hypervisor, Generally KVM or Xen. KVM is essentially kernel module extensions for QEMU (which is a software emulator). I hope this is helpful.
Vish On Aug 3, 2012, at 3:05 AM, Gaurab Basu <[email protected]> wrote: > 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 <[email protected]> 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 > > > > _______________________________________________ > Mailing list: https://launchpad.net/~openstack > Post to : [email protected] > Unsubscribe : https://launchpad.net/~openstack > More help : https://help.launchpad.net/ListHelp
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