2100-introduction-qcow2.html

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   5 <h1>Qcow2 images in qemu</h1>
   6
   7 <ul>
   8   <li>qcow2 is qemu's preferred image format</li>
   9   <li>qemu first used in-memory bitmaps internally to implement
  10     'block-stream' in qemu v1.1 (2012)</li>
  11   <li>qemu v2.6 (2016) added extension header 0x23852875 to qcow2v3
  12     for describing persistent bitmaps that live within the image</li>
  13   <li>an autoclear feature bit ensures that if any other program
  14     modifies the image without updating bitmaps, then the bitmaps are
  15     rendered inconsistent</li>
  16 </ul>
  17
  18 <p class="attribution">See also this 2015 KVM Forum
  19   presentation: <a href="https://www.youtube.com/watch?v=etIGp12RHRE">Backing
  20   Chain management in QEMU and libvirt</a>, Eric Blake</p>