On Thu, May 19, 2022 at 11:25 AM Andrei Verovski <andreil1(a)starlett.lv&gt; wrote: The short version is that you should always get a consistent backup, but it depends on the guest. oVirt does not use the “quiesce” option but it use the virDomainFSFreeze[1] and virDomainFSThaw[2] to get the same results. I think that Vinchin supports both snapshot based and incremental backup. In snapshot based backup, oVirt defaults to freeze the guest file system during snapshot creation, so you should get consistent backup. In incremental backup before 4.5, oVirt also freeze the filesystems when entering backup mode, so you should get consistent backup. In incremental backup in 4.5 and later, oVirt creates a temporary snapshot for every backup, and it freezes the file systems during the snapshot, so you should get a consistent backup. During incremental backup, the application can use the require_consistency[3] flag to fail to the backup if freezing the file systems failed. Note that in all cases, getting a consistent backup requires running qemu-guest-agent in the guest, and proper guest configuration if you need to do something special when fsFreeze or fsThaw are called. [1] https://libvirt.org/html/libvirt-libvirt-domain.html#virDomainFSFreeze [2] https://libvirt.org/html/libvirt-libvirt-domain.html#virDomainFSThaw [3] http://ovirt.github.io/ovirt-engine-api-model/master/#services/vm_backups... Nir