The Internet Suspend/Resume® (ISR) project
  What is the Internet Suspend/Resume system?

The Internet Suspend/Resume® (ISR) model of mobile computing cuts the tight binding between PC state and PC hardware. By layering a virtual machine on distributed storage, the ISR system lets the VM encapsulate execution and user customization state; distributed storage then transports that state across space and time.

The world we envision will retain the user customization aspect of personal computing. However, computers themselves will become a ubiquitous resource, much like light at the flip of a switch, water from a faucet, or the air we breathe. On demand, any Internet-connected computer could temporarily become your personal computer. Any machine will be able to acquire a user's unique customization and state from a server. When a user is done, his or her moditified state is erased from that machine and returned to the server. Loss, theft, or destruction of the machine will become only a minor inconvenience, not a catastrophic event.

The capabilities of the ISR model are realized through a combination of two well-studied technologies: virtual machine technology and distributed storage management systems. Virtual machine technology is used to capture the user's computing environment at the time of suspend. This environment consists of the user's operating system, applications, data files, customizations and the current execution state. By leveraging virtual machines, this state is re-instantiated directly on the machine at the resume site. This is not a thin-client approach. All process execution and computation takes place on hardware near the user. Therefore, an ISR system is able to provide the low-latency interactivity that users have come to expect.

The newest implementation of the ISR system, the OpenISR® platform, will make extensive use of Content Addressable Storage (CAS) for distributed storage. With CAS technology, users may leverage the storage associated with small devices and nearby computers to improve the performance of the ISR system without sacrificing security or robustness. In addition to extensive use of CAS, the OpenISR platform will also implement several key features:

  • VMM Agnosticism: users are not tied to a single virtual machine monitor.
  • Transient Thin-Client Mode: begin session as thin-client, then switch to thick-client after memory state is migrated in the background
  • Guest-Aware Migration: exploit information in the guest OS to aid in prefetching
  • Cross-Parcel Data Sharing: use Coda distributed filesystem for users' data

For more details on the history and design of the OpenISR system, see Pervasive Personal Computing in an Internet Suspend/Resume System (Satyanarayanan, et al., IEEE Internet Computing, Vol. 11, No. 2, March/April 2007) available for download here in PDF format.