[$] Changed-block tracking and differential backups in QEMU
The block layer of QEMU, the open-source
machine emulator and virtualizer, forms the backbone of many storage
virtualization features: the QEMU Copy-On-Write (QCOW2) disk-image file format,
disk image chains, point-in-time snapshots, backups, and more. At the
recently concluded 2020 KVM Forum
virtual event, Eric Blake gave a talk
on the current work in QEMU and libvirt
to make differential backups more powerful. As the name implies,
"differential backups" address the efficiency problems of full disk
backups: space usage and speed of backup creation.