Google Compute Engine uses KVM as the hypervisor, and supports guest images running Linux or FreeBSD. Google Compute Engine offers a RESTful API for managing resources such as disk, images, and instances. The default operating system provided by Google is Debian 6.0 and 7.0, other than Debian the only supported operating system is CentOS 6.2.
On February 25, 2013, Google announced that RightScale was their first reseller.
Every Google Compute Engine instance starts with a disk resource. Depending on the selected machine type, the instance may start with scratch disk space, persistent disk space, or both.
Scratch disk space is space tied to the life of an instance. If the instance is terminated for any reason, all scratch disk data is lost.
In contrast, persistent disks live beyond the life of an instance. They can be attached at boot time, or attached and detached from a running instance on demand. Persistent disks can also be attached in read-only mode to multiple instances at once.
Persistent disks offer additional features over scratch disks, such as persistent disk snapshots, booting from a persistent disk, and migrating persistent disks across zones.