How IS/R Works
"Internet Suspend/Resume is based on two fairly well understood technologies: network transport technologies and virtual machine technologies," says Intel Labs researcher Michael Kozuch. The network transport technologies are as familiar as the web, while virtual machine technologies are those that came out of such companies as VMware and ConnectX. IS/R runs on top of the virtual machine monitor, which emulates all of the portions of a personal computer. The code thinks it's running on real hardware, when in fact it's actually talking to real hardware through another piece of software. "The guest software has to believe the new machine is the same as the old machine," says Kozuch. And because the virtual machine does such a good job of pretending to be what it's not, it's perfect for mixed IT environments: "If we have a machine in a public space, someone can walk up and make this [his] FreeBSD box...and someone else make this [her] Linux box."
Of course, speed across the Internet is a conundrum for researchers. One solution is content-addressable storage (CAS)leaving some of the content on a drive near the Resume box, so the user doesn't have to wait for it to download the next day. Resume times are not too bad at DSL speeds and better, even for multi-gigabyte environments (see Figure 2).
Figure 2 Content-addressable storage (CAS) allows users to save Resume time by storing some content securely on nearby devices, rather than waiting for everything to reload from scratch.