More KVM performance thanks to an optimized disk configuration
KVM has many ways to map virtual disks on the host system. The appropriate choice of disk format has an effect not only on the speed of I/O operations but also on snapshots and backups.
Most virtualization systems present virtual hard disks to the guest as ordinary IDE, SCSI, or SATA drives. For the guest, it thus looks as if they have access to a normal hard disk. But, in fact, the virtualization system must emulate the IDE, SCSI, or SATA bus whenever data access occurs. On the virtual machine, an appropriate driver takes care of data access.