Gionatan Danti
2022-Nov-26 09:36 UTC
[Question] Which qcow2 options could be inherited to snapshot/blockcopy?
Il 2022-11-21 10:30 Peter Krempa ha scritto:> In regards to the 'compat' option in terms of snapshots/blockcopy, we > don't set it and thus use the qemu default. Since both operations > create > a new image with an existing qemu instance, the default new qemu format > is okay.Hi, some idea on why creating a qcow2 volume and snapshotting it via a backing file results in two qcow2 files with different format (v2 vs v3)? Example below: # volume creation [root at whitehole ~]# virsh vol-create-as default zzz.qcow2 1G --format qcow2 Vol zzz.qcow2 created [root at whitehole ~]# qemu-img info /var/lib/libvirt/images/zzz.qcow2 image: /var/lib/libvirt/images/zzz.qcow2 file format: qcow2 virtual size: 1 GiB (1073741824 bytes) disk size: 16.5 KiB cluster_size: 65536 Format specific information: compat: 0.10 compression type: zlib refcount bits: 16 [root at whitehole ~]# file /var/lib/libvirt/images/zzz.qcow2 /var/lib/libvirt/images/zzz.qcow2: QEMU QCOW2 Image (v2), 1073741824 bytes # snapshot creation [root at whitehole ~]# virsh snapshot-create-as zzz --name zsnap1 --disk-only Domain snapshot zsnap1 created [root at whitehole ~]# qemu-img info /var/lib/libvirt/images/zzz.zsnap1 image: /var/lib/libvirt/images/zzz.zsnap1 file format: qcow2 virtual size: 1 GiB (1073741824 bytes) disk size: 16.5 KiB cluster_size: 65536 backing file: /var/lib/libvirt/images/zzz.qcow2 backing file format: qcow2 Format specific information: compat: 1.1 compression type: zlib lazy refcounts: false refcount bits: 16 corrupt: false extended l2: false [root at whitehole ~]# file /var/lib/libvirt/images/zzz.zsnap1 /var/lib/libvirt/images/zzz.zsnap1: QEMU QCOW2 Image (v3), has backing file (path /var/lib/libvirt/images/zzz.qcow2), 1073741824 bytes Regards. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti at assyoma.it - info at assyoma.it GPG public key ID: FF5F32A8
Gionatan Danti
2022-Dec-11 19:36 UTC
[Question] Which qcow2 options could be inherited to snapshot/blockcopy?
Il 2022-11-26 10:36 Gionatan Danti ha scritto:> Il 2022-11-21 10:30 Peter Krempa ha scritto: >> In regards to the 'compat' option in terms of snapshots/blockcopy, we >> don't set it and thus use the qemu default. Since both operations >> create >> a new image with an existing qemu instance, the default new qemu >> format >> is okay. > > Hi, some idea on why creating a qcow2 volume and snapshotting it via a > backing file results in two qcow2 files with different format (v2 vs > v3)? Example below: > > # volume creation > [root at whitehole ~]# virsh vol-create-as default zzz.qcow2 1G --format > qcow2 > Vol zzz.qcow2 created > > [root at whitehole ~]# qemu-img info /var/lib/libvirt/images/zzz.qcow2 > image: /var/lib/libvirt/images/zzz.qcow2 > file format: qcow2 > virtual size: 1 GiB (1073741824 bytes) > disk size: 16.5 KiB > cluster_size: 65536 > Format specific information: > compat: 0.10 > compression type: zlib > refcount bits: 16 > > [root at whitehole ~]# file /var/lib/libvirt/images/zzz.qcow2 > /var/lib/libvirt/images/zzz.qcow2: QEMU QCOW2 Image (v2), 1073741824 > bytes > > # snapshot creation > [root at whitehole ~]# virsh snapshot-create-as zzz --name zsnap1 > --disk-only > Domain snapshot zsnap1 created > > [root at whitehole ~]# qemu-img info /var/lib/libvirt/images/zzz.zsnap1 > image: /var/lib/libvirt/images/zzz.zsnap1 > file format: qcow2 > virtual size: 1 GiB (1073741824 bytes) > disk size: 16.5 KiB > cluster_size: 65536 > backing file: /var/lib/libvirt/images/zzz.qcow2 > backing file format: qcow2 > Format specific information: > compat: 1.1 > compression type: zlib > lazy refcounts: false > refcount bits: 16 > corrupt: false > extended l2: false > > [root at whitehole ~]# file /var/lib/libvirt/images/zzz.zsnap1 > /var/lib/libvirt/images/zzz.zsnap1: QEMU QCOW2 Image (v3), has backing > file (path /var/lib/libvirt/images/zzz.qcow2), 1073741824 bytes > > Regards.Hi all, anyone with some ideas/suggestions? Regards. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti at assyoma.it - info at assyoma.it GPG public key ID: FF5F32A8