Patent ID: 8112392

Claim:
A computer-implemented method comprising: identifying a virtualized application comprising a read-only virtualization sublayer and a read-write virtualization sublayer, wherein: the read-only virtualization sublayer is configured such that at least one user is prohibited from modifying the read-only virtualization sublayer; the read-write virtualization sublayer is configured such that the at least one user is permitted to modify the read-write virtualization sublayer; the read-only virtualization sublayer comprises a base state of the virtualized application and the read-write virtualization sublayer is configured to store changes to the base state of the virtualized application; the read-only and read-write virtualization sublayers isolate the virtualized application from a base file system; the read-only and readwrite virtualization sublayers, when activated, overlay the base file system such that the virtualized application appears to an operating system as though it were installed in the base file system; determining a first difference between the read-only virtualization sublayer and the read-write virtualization sublayer at a first point in time; using the first difference between the read-only virtualization sublayer and the read-write virtualization sublayer to create a first snapshot that represents a state of the virtualized application at the first point in time.