Computer World. Матросова Т.А. - 52 стр.

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51
extended systems architecture made up of many powerful, self-contained
workstations that coexist and communicate on a network. Instead, Plan 9 creates a
networked architecture made up of three key components each designed for a
particular function and dependent on the others.
Gnot A Workstation
The Plan 9 architecture consists of what its creators call a «CPU server», a
fileserver and a terminal. The CPU server, implemented as a multiprocessor system
takes on all computation tasks. It has no local storage and instead relies on associated
remote fileservers for storage. The CPU server communicates via a 20-megabyte per
second direct memory access (DM) link with fileservers that are equipped with lots of
solid - state, magnetic and optical memory.
The servers use a nonstandard, efficient protocol to communicate over standard
phone lines with a dedicated Plan 9 terminal called a Gnot. Plan 9 researchers say
they are fully aware that calling the Gnot a terminal rather than a workstation implies
a return to an older, more centralized style of computing. That, they say, is exactly
the idea.
Although the current prototype Gnot is plenty powerful–it's based on a 25-
megahertz 68020 processor and has a 1,024 x 1,024 pixel display–the Plan 9
terminal, like terminals of old, is designed as an anonymous node on the network, not
a full-fledged workstation.
«If you have a network of workstations, each workstation has some files of its
own, and somebody has to worry about [managing] that,» says Peter Weinberger,
Bell Labs computing principles research department head. «Here [with Plan 9] there's
just a fileserver. I have files, but the workstation doesn't have any files.» This strategy
makes a Plan 9 network much easier to manage than one made up of full-function
workstations, says Weinberger. It also makes security easier to handle.
Complementing Plan 9's hardware architecture is a unique method for naming
files and creating name spaces. When a user sits down at a Plan 9 terminal, he or she
selects from a set of available services, and Plan 9 automatically creates a name space
by joining the user's private name space with the service's name spaces.
Researc hers say the Plan 9 arc hitecture w ill not on ly be easier to use and
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minister but also better able to keep up with swiftly evolving computer technology
advances. By expressly isolating the terminal, researchers say, Plan 9 can take
advantage of the most rapid improvements in chip speed and display technologies
without having to replace whole workstations or large amounts of storage.
Plan 9 researchers insist they aren't trying to replace UNIX. «It's not as if any-
one expects UNIX to go away. This [Plan 9] is just complementary, supplementary,»
says Weinberger. In fact, although UNIX and Plan 9 are not compatible, Plan 9 can
interoperate and share files with UNIX. A large percentage of the 60 P lan 9 users
inside Bell Labs currently use the operating system primarily to access UNIX
applications and files.
Nor do researchers expect Plan 9 to become available outside Bell Labs any-
time soon. Although lately Bell Labs's management has been publicly discussing the

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