Test Day:2009-09-17 Virtualization qcow2

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Thursday Sep 17, 2009 All day #fedora-test-day (webchat)


What to test?

This part of today's Fedora Test Day will focus on testing virt-manager, libvirt and qemu-kvm support for the qcow2 image format.

This is related to the KVM qcow2 Performance feature in Fedora 12. If we're to advertise the format's improved performance, we better test that people can use the format!

If you come to this page after the test day is completed, your testing is still valuable, and you can use the information on this page to test qcow2 support and provide feedback.

Who's available

Cole Robinson and Kevin Wolf (IRC nick kwolf, GMT+2h) are your hosts for today.

The following people have also agreed to be available for testing, workarounds, bug fixes, and general discussion:

  • add your name here

What's needed to test

Test Cases

Things to test, roughly in dependency order:

  1. QA:Testcase virt-install using qcow2
  2. QA:Testcase virt-manager install using qcow2
  3. QA:Testcase qemu-img convert from raw to qcow2
  4. QA:Testcase qemu-img create snapshot

Advanced aspects

If you want to play a bit more with qcow2 and the test cases suggested above are not enough for you, there are some additional features that cannot be accessed with the management tools (so they are not top priority to be tested), but you still can use them by invoking qemu-img and qemu manually.

When creating images with qemu-img, you can change some default options using the -o parameter. For example you could create a fairly non-standard image using qemu-img create -f qcow2 -o encryption,cluster_size=32k,backing_file=base.vmdk image.qcow2 10G. To get an overview of the supported options, you can use qemu-img create -f qcow2 -o ?.

The following list contains some suggestions on what you could test:

  • Encrypted images (-o encryption)
  • Varying cluster sizes (-o cluster_size=size where size is between 512 and 64k). Smaller cluster can save some space on almost empty disks, larger clusters are faster usually.
  • Backing files (-o backing_file=file). The new image is based on the given backing file and only differences are saved into the qcow2 file. Try usinh different formats for the backing file, it doesn't need to be qcow2.
  • Commit back the changes from a qcow2 image to its backing file (qemu-img commit or the commit command in the qemu monitor)
  • Compressed images: When converting an image, you can have the resulting qcow2 image compressed (qemu-img convert -O qcow2 -c ...)
  • Combine things: Snapshots on an encrypted image with a compressed backing file...

Issues that were identified

Tester Description Bug references Status