From: Greg Green (ggreen_at_cs.washington.edu)
Date: Mon Feb 02 2004 - 12:09:05 PST
Grapevine was a distributed messaging, authentication, and
registration service in operation at Xerox. It was distributed over a
large geographical space, with varying speed connections between the
nodes. The data on the system was replicated over many servers so that
it was not reliant on any one server.
The registration service had user's and groups. The groups were used
as mailing lists, and also for file system ACL security checking. The
system was designed to scale up to 30 servers and 10000 users. The
practical limits were close to this design. Some changes would have to
be made to make it reach that limit.
The paper was mostly about the problems found when using a system of
this size with this type of reliability. There were problems with
mailing list administration, disks getting full, corrupted disks,
etc. One set of interesting problems related to how the distributed
nature of the system would "show through" to the user and cause
problems. The system appeared to be quite reliable.
I found that this paper was interesting in that you could see the
beginnings of our current email. Some of the problems that they
mentioned still are not solved in the current systems. There was a lot
of discussion of how to distribute the source of information to
increase performance. Since I don't have any distributed system
experience, I don't know whether that means that the system wasn't
designed correctly, or if this is a large part of implementing a
proper distributed system. Another interesting thing was having the
inboxes replicated, so that a user could still get their mail even if
the primary server wasn't working. Since I work on a large Exchange
Server network, (which breaks fairly often), I wish that this feature
was available to us.
-- Greg Green
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