cluster partition problem

Mark Hayden hayden at pa.dec.com
Sun Nov 7 16:25:25 MST 1999


>On Sun, 07 Nov 1999 19:49:24 +0100, Andrew Harris wrote: 
>
>>Has anyone seen: http://www.cs.cornell.edu/Info/Projects/Ensemble/overview.ht
m
>>l ?
>>Can that help with this problem?
>
>Don't know specifically about the software capabilities, but it appears 
>to have a wacky license.

I'm the primary designer and implementer of Ensemble.  I think you
would find Ensemble useful in building cluster management tools.  In
fact, others have used Ensemble for exactly this purpose, including
the Rodagroup's Polyserve Understudy cluster management system
(http://www.polyserve.com/) and in managing the 10Six (www.10six.com)
game servers.

Regarding the Ensemble license, I don't believe it has any strange
restrictions.  I'm not a lawyer, but I believe it could be described
as a BSD-style license.  I've included the license below and I'd be
interested in hearing any explicit concerns.

I won't attempt to describe Ensemble here.  If you are interested in
learning about it, more information can be found at the Ensemble web
site:

  http://www.cs.cornell.edu/Info/Projects/Ensemble/overview.html

and the tutorial and reference manuals (included with the software).
Chapter 2 of my phd thesis:

  http://cs-tr.cs.cornell.edu:80/Dienst/UI/1.0/Display/ncstrl.cornell/TR98-1662

is a brief introduction to group membership toolkits and Ensemble in
particular.  If after reading the documentation you still do not
understand what Ensemble does, I strongly recommend downloading the
software and trying out some of the demo programs.  There is a binary
RPM for Linux.  Follow the brief instructions in the tutorial
(tut.ps) and try out the 'mtalk' (multiperson talk) and 'ensemble' (a
text-based interface to the protocols) demos.

Regarding the 'split-brain' partitioning scenarios that have been
discussed in this mailing list, Ensemble was designed from the
ground-up to handle partitioning.  It will detect both when
partitioning occurs as well as when the partitioning heals.  In fact,
the Ensemble protocols start processes in "singleton" partitions and
then merge with other processes as they are detected.  Ensemble also
provides support for tracking the primary partition.

There has been some discussion on this mailing list about security.
Ensemble includes a suite of configurable security protocols.

If you have any questions about Ensemble, I'd be happy to try
answering them.  Additionally, there is a mailing list for Ensemble
users.  There are instructions at the Ensemble web site on how to
subscribe.

--Mark








LICENSE TERMS AND CONDITIONS


1.  The 'Software', below, refers to the Ensemble system, developed by
    the Horus Project  (in either source-code, object-code or executable-code
    form), and related documentation, and a 'work based on the Software' means
    a work based on either the Software, on part of the Software, or on any
    derivative work of the Software under copyright law: that is, a work
    containing all or a portion of the Ensemble System, either verbatim or
    with modifications.  Each licensee is addressed as 'you' or 'Licensee.'


2.  Cornell University as the parent organization of the Horus Project
    holds copyrights in the Software.  The copyright holder reserves all
    rights except those expressly granted to licensees, and U.S.  Government
    license rights.


3.  Permission is hereby granted to use, copy, modify, and to redistribute
    to others.  If you distribute a copy or copies of the Software, or you
    modify a copy or copies of the Software or any portion of it, thus
    forming a work based on the Software, and make and/or distribute copies
    of such work, you must meet the following conditions:


    a)  If you make a copy of the Software (modified or verbatim) it must
        include the copyright notice and this license.


    b)  You must cause the modified Software to carry prominent notices
        stating that you changed specified portions of the Software.



4.  LICENSEE AGREES THAT THE EXPORT OF GOODS AND/OR TECHNICAL
    DATA FROM THE UNITED STATES MAY REQUIRE SOME FORM OF EXPORT
    CONTROL LICENSE FROM THE U.S. GOVERNMENT AND THAT FAILURE TO
    OBTAIN SUCH EXPORT CONTROL LICENSE MAY RESULT IN CRIMINAL
    LIABILITY UNDER U.S. LAWS.


5.  Portions of the Software resulted from work developed under a U.S.
    Government Contract and are subject to the following license: the
    Government is granted for itself and others acting on its behalf a
    paid-up, nonexclusive, irrevocable worldwide license in this computer
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