virt-sparsify ?

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ToddAndMargo

Wednesday, 9 November 2022 Wed, 9 Nov '22

10:28 a.m.

Any downside to ths tool? https://libguestfs.org/virt-sparsify.1.html

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ToddAndMargo

Wednesday, 9 November Wed, 9 Nov

10:32 a.m.

On 11/9/22 08:28, ToddAndMargo via users wrote:

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Any downside to ths tool? https://libguestfs.org/virt-sparsify.1.html

This is what I am looking at: $ du -sh *.qcow* 4.6G KVM-Android.qcow2 72M KVM-BackupDrive.w10.qcow2 36M KVM-BackupDrive.w11.qcow2 72M KVM-BackupDrive.w7.qcow2 17G KVM-Fedora-23-AutoScan.qcow2 38G KVM-Fedora-Xfce.qcow2 8.1G KVM-LiveCDs.qcow2 61G KVM-W10.qcow2 60G KVM-W11.qcow2 40G KVM-W7.qcow 46M KVM-W7.qcow2 4.0K KVM-WinXP.qcow.02-13-2015.lin-bak.txt $ ls -lh *.qcow* -rwxrw-rw-. 1 root root 11G May 5 2022 KVM-Android.qcow2 -rw-------. 1 qemu qemu 72M Nov 6 21:44 KVM-BackupDrive.w10.qcow2 -rw-------. 1 qemu qemu 36M Nov 9 00:31 KVM-BackupDrive.w11.qcow2 -rw-------. 1 qemu qemu 72M Nov 9 07:34 KVM-BackupDrive.w7.qcow2 -rwxrw-rw-. 1 todd users 17G Apr 23 2019 KVM-Fedora-23-AutoScan.qcow2 -rwxrw-rw-. 1 todd users 40G Jul 22 22:03 KVM-Fedora-Xfce.qcow2 -rwxrw-rw-. 1 todd users 8.1G Jul 17 2017 KVM-LiveCDs.qcow2 -rwxrw-rw-. 1 qemu qemu 61G Nov 6 21:44 KVM-W10.qcow2 -rw-------. 1 qemu qemu 61G Nov 9 00:31 KVM-W11.qcow2 -rwxrw-rw-. 1 qemu qemu 40G Nov 9 07:34 KVM-W7.qcow -rwxrw-rw-. 1 qemu qemu 2.1G Nov 9 07:34 KVM-W7.qcow2 -rwxrw-rw-. 1 todd users 46 Feb 14 2015 KVM-WinXP.qcow.02-13-2015.lin-bak.txt

Jamie Fargen

10:34 a.m.

There shouldn't be any downside, but per the doc the virtual machine must be off, no other tools used concurrently. It seems that virt-sparsify can be used with an input and output image file or operate on the image file directly, the first option being the safest in the event of corruption on the new disk image the original image can reverted back to use. Regards, -Jamie On Wed, Nov 9, 2022 at 11:29 AM ToddAndMargo via users <users(a)lists.fedoraproject.org> wrote: > > Any downside to ths tool? > > https://libguestfs.org/virt-sparsify.1.html > _______________________________________________ > users mailing list -- users(a)lists.fedoraproject.org > To unsubscribe send an email to users-leave(a)lists.fedoraproject.org > Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ > List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines > List Archives: https://lists.fedoraproject.org/archives/list/users@lists.fedoraproject.org > Do not reply to spam, report it: https://pagure.io/fedora-infrastructure/new_issue

ToddAndMargo

Wednesday, 16 November Wed, 16 Nov

8:20 p.m.

On 11/9/22 08:28, ToddAndMargo via users wrote:

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Any downside to ths tool? https://libguestfs.org/virt-sparsify.1.html

My befores and afters # du -sh KVM-W7.qcow KVM-W7.qcow2 KVM-W10.000.qcow2 KVM-W10.qcow2 KVM-W11.000.qcow2 KVM-W11.qcow2 40G KVM-W7.qcow 27G KVM-W7.qcow2 61G KVM-W10.000.qcow2 46G KVM-W10.qcow2 60G KVM-W11.000.qcow2 21G KVM-W11.qcow2

ToddAndMargo

Monday, 12 December Mon, 12 Dec

6:53 a.m.

On 11/9/22 08:28, ToddAndMargo wrote:

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Any downside to ths tool? https://libguestfs.org/virt-sparsify.1.html

Yes, BIG, BIG downside! dump/restore can not restore the fiel correctly. dump restores a qcows drive as a blank drive https://bugzilla.redhat.com/show_bug.cgi?id=2152393

Patrick O'Callaghan

8:53 a.m.

On Mon, 2022-12-12 at 04:53 -0800, ToddAndMargo via users wrote:

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On 11/9/22 08:28, ToddAndMargo wrote: > Any downside to ths tool? > > https://libguestfs.org/virt-sparsify.1.html Yes, BIG, BIG downside! dump/restore can not restore the fiel correctly. dump restores a qcows drive as a blank drive

Restor (not dump) will restore sparse files as expanded files, i.e. with the uncopied sections filled in with nulls. That is entirely normal (cp and most other utilities will do the same thing unless told otherwise). The resulting file should look exactly the same as the original, except for occupying more physical space. However virt-sparsify presumably also messes with the guest filesystem metadata (inode, FAT, whatever) when doing this, so that the guest system still sees a functioning filesystem. If so, I wouldn't expect dump/restor to recognise that, so maybe that's where the problem lies. poc

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Jamie Fargen
Patrick O'Callaghan
ToddAndMargo