I did some testing with a WindowsXP guest, that I have and could test on. It seems that this behavior is not present at the beginning. But at the moment we create a snapshot it is starting to write on top of the current size. So, it is like this: 1. Image is:
Code: qemu-img info WindowsXP.img image: WindowsXP.img file format: qcow2 virtual size: 15G (15728640000 bytes) disk size: 13G cluster_size: 65536 I write some files and it doesn't become more than that. 2. I delete some files, then write again and it doesn't changes size. 3. I create a snapshot: Code: qemu-img info WindowsXP.img image: WindowsXP.img file format: qcow2 virtual size: 15G (15728640000 bytes) disk size: 13G cluster_size: 65536 Snapshot list: ID TAG VM SIZE DATE VM CLOCK 1 test 0 2012-07-17 09:52:25 00:00:00.000 4. I write something with a size of 587MB and it becomes larger (with 587MB) Code: du -sm WindowsXP.img 14102 WindowsXP.img 5. I delete it and then write it again. It becomes more larger... (again with another 587MB) Code: du -sm WindowsXP.img 14703 WindowsXP.img 6. I delete it and then write it again. It doesn't change this time. 7. I write a copy of it. It becomes larger (with 587MB) Code: du -sm WindowsXP.img 15309 WindowsXP.img 8. I delete it and then write it again. It doesn't change this time. 9. I write a copy of it. It becomes larger again (with 587MB) Code: du -sm WindowsXP.img 16010 WindowsXP.img 10. I write another copy of it and it stays the same. Code: du -sm WindowsXP.img 16010 WindowsXP.img 11. I write another copy of it and becomes larger again. Code: du -sm WindowsXP.img 16913 WindowsXP.img Code: qemu-img info WindowsXP.img image: WindowsXP.img file format: qcow2 virtual size: 15G (15728640000 bytes) disk size: 17G cluster_size: 65536 Snapshot list: ID TAG VM SIZE DATE VM CLOCK 1 test 0 2012-07-17 09:52:25 00:00:00.000 12. Create a snapshot. 13. I write a copy of it. It becomes larger again (with 587MB) Code: du -sm WindowsXP.img 17572 WindowsXP.img 14. I delete both of the snapshots. 15. I delete the file (in guest with the size of 587MB) and write it again. No change in size. 16. I delete the file again and write it again. No change in size. 17. Create a snapshot. 18. I delete the file again and write it again. No change in size. 19. Delete the file. 20. Create a snapshot. 21. Write the file again. No change in size. Well from all this, I can conclude that most probably: 1. The problem occurs only when there is an internal snapshot present. 2. The problem is not "by design" because the behavior is not consistent (for example, 13. and 21. should be with the same result, but they arent't).. At the end of the day, after these procedures (4 creations of snapshots, 2 deletions and some writing and deleting of internal guest files) the result is this: Code: qemu-img info WindowsXP.img image: WindowsXP.img file format: qcow2 virtual size: 15G (15728640000 bytes) disk size: 17G cluster_size: 65536 Snapshot list: ID TAG VM SIZE DATE VM CLOCK 1 test2 0 2012-07-17 14:55:17 00:00:00.000 2 test3 0 2012-07-17 15:27:43 00:00:00.000 and Code: ls -lsh WindowsXP.img 18G -rw------- 1 libvirt-qemu kvm 18G Jul 17 15:43 WindowsXP.img -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1025244 Title: qcow2 image increasing disk size above the virtual limit To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/1025244/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
