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qemu-img is not able to use information from the image metadata (like the information in qemu-img map). This information can be used to speed up conversion of images. Example: $ qemu-img create prova.img 1G Formatting 'prova.img', fmt=raw size=1073741824 Without feature: $ time qemu-img convert -f raw -O raw -t none prova.img prova2.img real 0m0.504s user 0m0.129s sys 0m0.347s With feature: $ time ./qemu-img convert -f raw -O raw -t none prova.img prova2.img real 0m0.281s user 0m0.002s sys 0m0.009s The effect is even more visible with the "-p" option to qemu-img.
Reproduce and verify this issue with the same steps as comment #0. # qemu-img create prova.img 1G Formatting 'prova.img', fmt=raw size=1073741824 # qemu-img info prova.img image: prova.img file format: raw virtual size: 1.0G (1073741824 bytes) disk size: 0 With the unfixed qemu-kvm version: # rpm -q qemu-kvm qemu-kvm-1.5.3-30.el7.x86_64 # time qemu-img convert -f raw -O raw -t none prova.img prova1.img real 0m0.435s user 0m0.058s sys 0m0.308s With the fixed qemu-kvm version: # rpm -q qemu-kvm qemu-kvm-1.5.3-38.el7.x86_64 # time qemu-img convert -f raw -O raw -t none prova.img prova2.img real 0m0.024s user 0m0.002s sys 0m0.001s Base on above, this issue has been fixed correctly. Move to VERIFIED status. Best Regards, sluo
This request was resolved in Red Hat Enterprise Linux 7.0. Contact your manager or support representative in case you have further questions about the request.