Olive (software archive) (nonfiction)

Olive ("Open Library of Images for Virtualized Execution") is an experimental service from Carnegie Mellon University that stores images of old processors, as well as the old operating systems that ran on top of them, along with software packages for those old OSes; this allows users to access old data from obsolete systems inside simulations of the computers that originally ran that data, using the original operating systems and applications.

Mahadev Satyanarayananm professor of computer science at Carnegie Mellon University in Pittsburgh, writes:

To understand how Olive can bring old computing environments back to life, you have to dig through quite a few layers of software abstraction. At the very bottom is the common base of much of today’s computer technology: a standard desktop or laptop endowed with one or more x86 microprocessors. On that computer, we run the Linux operating system, which forms the second layer in Olive’s stack of technology.

Sitting immediately above the operating system is software written in my lab called VMNetX, for Virtual Machine Network Execution. A virtual machine is a computing environment that mimics one kind of computer using software running on a different kind of computer. VMNetX is special in that it allows virtual machines to be stored on a central server and then executed on demand by a remote system. The advantage of this arrangement is that your computer doesn’t need to download the virtual machine’s entire disk and memory state from the server before running that virtual machine. Instead, the information stored on disk and in memory is retrieved in chunks as needed by the next layer up: the virtual-machine monitor (also called a hypervisor), which can keep several virtual machines going at once.

Each one of those virtual machines runs a hardware emulator, which is the next layer in the Olive stack. That emulator presents the illusion of being a now-obsolete computer—for example, an old Macintosh Quadra with its 1990s-era Motorola 68040 CPU. (The emulation layer can be omitted if the archived software you want to explore runs on an x86-based computer.)

The next layer up is the old operating system needed for the archived software to work. That operating system has access to a virtual disk, which mimics actual disk storage, providing what looks like the usual file system to still-higher components in this great layer cake of software abstraction.

Above the old operating system is the archived program itself. This may represent the very top of the heap, or there could be an additional layer, consisting of data that must be fed to the archived application to get it to do what you want.

The upper layers of Olive are specific to particular archived applications and are stored on a central server. The lower layers are installed on the user’s own computer in the form of the Olive client software package. When you launch an archived application, the Olive client fetches parts of the relevant upper layers as needed from the central server.

Fiction cross-reference

• Gnomon algorithm
• Gnomon Chronicles

Nonfiction cross-reference

• Software (nonfiction)

External links:

• OLIVE: a system for emulating old OSes on old processors that saves old data from extinction @ Boing Boing
• Carnegie Mellon is Saving Old Software from Oblivion - "A prototype archiving system called Olive lets vintage code run on today’s computers"