Vish: For documentation purposes, if the user wants to be able to do snapshots, what combinations of the following three variables are allowed?
1. original image format (qcow2 | raw) 2. use_cow_image flag (true | false) 3. force_raw_images flag (true | false) Take care, Lorin -- Lorin Hochstein Lead Architect - Cloud Services Nimbis Services, Inc. www.nimbisservices.com On Apr 10, 2012, at 1:32 AM, Vishvananda Ishaya wrote: > 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 >> >> williamherrych...@gmail.com >> >> _______________________________________________ >> Mailing list: https://launchpad.net/~openstack >> Post to : openstack@lists.launchpad.net >> Unsubscribe : https://launchpad.net/~openstack >> More help : https://help.launchpad.net/ListHelp > > _______________________________________________ > Mailing list: https://launchpad.net/~openstack > Post to : openstack@lists.launchpad.net > Unsubscribe : https://launchpad.net/~openstack > More help : https://help.launchpad.net/ListHelp
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