You can disable using backing files with the following config: use_cow_images=false
You should be aware that you likely won't be able to snapshot images unless you make sure to upload them all in qcow format and also set: force_raw_images=false On Apr 9, 2012, at 9:37 PM, William Herry wrote: > Hi > > I read from an article that said use preallocation can improve disk I/O > performance in kvm, when I add it to openstack, suck error come to me > > (nova.rpc.amqp): TRACE: Stderr: 'Backing file and preallocation cannot be > used at the same time\nqemu-img: > /usr/local/lib/python2.7/dist-packages/nova-2012.1-py2.7.egg/instances/instance-0000000e/disk: > error while creating qcow2: Invalid argument\n' > > I was added it to utils.py in virt/libvirt directory (line 77) > > def create_cow_image(backing_file, path): > """Create COW image > > Creates a COW image with the given backing file > > :param backing_file: Existing image on which to base the COW image > :param path: Desired location of the COW image > """ > execute(FLAGS.qemu_img, 'create', '-f', 'qcow2', '-o', > 'preallocation=metadata,cluster_size=2M,backing_file=%s' % > backing_file, path) > > here is the article: > http://itscblog.tamu.edu/improve-disk-io-performance-in-kvm/ > > so what is Backing file for, can I disable it for use preallocation cause I > can't got both > > Thanks > > -- > > =========================== > William Herry > > [email protected] > > _______________________________________________ > 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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