<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>Vish:</div><div><br></div><div>For documentation purposes, if the user wants to be able to do snapshots, what combinations of the following three variables are allowed?</div><div><br></div><div>1. original image format (qcow2 | raw)</div><div>2. use_cow_image flag (true | false)</div><div>3. force_raw_images flag (true | false)</div><div><br></div><div><br></div><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>Take care,</div><div><br></div><div>Lorin</div><div>--</div><div>Lorin Hochstein</div><div>Lead Architect - Cloud Services</div><div>Nimbis Services, Inc.</div><div><a href="https://www.nimbisservices.com/">www.nimbisservices.com</a></div><div><br></div></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></span><br class="Apple-interchange-newline">
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<br><div><div>On Apr 10, 2012, at 1:32 AM, Vishvananda Ishaya wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">You can disable using backing files with the following config:<div>use_cow_images=false</div><div><br></div><div>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:</div><div>force_raw_images=false</div><div><br><div><div>On Apr 9, 2012, at 9:37 PM, William Herry wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Hi<br><br>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<br><br>(nova.rpc.amqp): TRACE: Stderr: <span style="color:rgb(255,0,0)">'Backing file and preallocation cannot be used at the same time</span>\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'<br>
<br>I was added it to utils.py in virt/libvirt directory (line 77)<br><br>def create_cow_image(backing_file, path):<br> """Create COW image<br><br> Creates a COW image with the given backing file<br><br>
:param backing_file: Existing image on which to base the COW image<br> :param path: Desired location of the COW image<br> """<br> execute(FLAGS.qemu_img, 'create', '-f', 'qcow2', '-o',<br>
'preallocation=metadata,cluster_size=2M,backing_file=%s' %<br> backing_file, path)<br><br>here is the article: <a href="http://itscblog.tamu.edu/improve-disk-io-performance-in-kvm/">http://itscblog.tamu.edu/improve-disk-io-performance-in-kvm/</a><br clear="all">
<br>so what is Backing file for, can I disable it for use preallocation cause I can't got both<br><br>Thanks<br><br>-- <br><font><span style="font-family:courier new,monospace;color:rgb(51,51,255)"><br>===========================</span><span style="font-family:courier new,monospace;color:rgb(51,51,255)"></span><br>
William Herry<br><br style="font-family:courier new,monospace;color:rgb(51,51,255)"><span style="font-family:courier new,monospace;color:rgb(0,0,0)"><a href="mailto:WilliamHerryChina@Gmail.com">WilliamHerryChina@Gmail.com</a></span></font><font><span style="font-family:courier new,monospace;color:rgb(0,0,0)"></span><br>
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