> What are you trying to achieve? If you just want to make small guests > (eg for a guest library for testing) then virt-sparsify is possibly > the tool you want. Yep, I was just try to make the guest images small for testing, but if the performance was good then I would consider using in production too. I've given virt-sparsify a go, and it has recovered some space... Before... root@proliantml110:/var/lib/libvirt/images# du -h test-centos6-gpt.img.original 1.3G test-centos6-gpt.img.original root@proliantml110:/var/lib/libvirt/images# qemu-img info test-centos6-gpt.img.original image: test-centos6-gpt.img.original file format: qcow2 virtual size: 10G (10737418240 bytes) disk size: 1.2G cluster_size: 65536 Running virt-sparsify... root@proliantml110:/var/lib/libvirt/images# virt-sparsify test-centos6-gpt.img.original test-centos6-gpt.img.sparsified Create overlay file to protect source disk ... Examine source disk ... Fill free space in /dev/vda1 with zero ... Copy to destination and make sparse ... Sparsify operation completed with no errors. Before deleting the old disk, carefully check that the target disk boots and works correctly. After ... root@proliantml110:/var/lib/libvirt/images# du -h test-centos6-gpt.img.sparsified 882M test-centos6-gpt.img.sparsified root@proliantml110:/var/lib/libvirt/images# qemu-img info test-centos6-gpt.img.sparsified image: test-centos6-gpt.img.sparsified file format: qcow2 virtual size: 10G (10737418240 bytes) disk size: 882M cluster_size: 65536 The benefits remained when compressing the sparsified image too... root@proliantml110:/var/lib/libvirt/images# du -h test-centos6-gpt.img.sparsified-compressed 289M test-centos6-gpt.img.sparsified-compressed root@proliantml110:/var/lib/libvirt/images# du -h test-centos6-gpt.img.original-compressed 369M test-centos6-gpt.img.original-compressed So thanks for the tip! I'm also going to experiment with backing images to build a base library of gold images. Cheers, Paul
