SPACE SNAPSHOTS

Data is identified that defines a known good state for a current operating system. The identified data includes read-only sets that are not updated during operation of the computing device, and modifiable sets that can be updated during operation of the computing device. The read-only sets are captured on an opportunistic basis and the modifiable sets are captured when the computing device is to be rebooted. A first and second virtual disk are allocated as snapshots of the identified data. The first virtual disk is updated to generate an updated state. The updates to the first virtual disk are isolated from the second virtual disk. The second virtual disk is maintained as an immutable snapshot of the identified data. In response to a failed reboot with the updated state, the computing device reverts to the known good state using the snapshot of the identified data.