Xref: utzoo news.sysadmin:508 news.software.b:1071
Path: utzoo!mnetor!uunet!husc6!bloom-beacon!oberon!mcooper
From: mcooper@oberon.USC.EDU (Michael A. Cooper)
Newsgroups: news.sysadmin,news.software.b
Subject: Keeping multiple news machines in sync
Message-ID: <6263@oberon.USC.EDU>
Date: 16 Jan 88 18:49:04 GMT
Reply-To: mcooper@oberon.usc.edu (Michael A. Cooper)
Organization: USC Computing Services, Los Angeles
Lines: 59



	[ We are running B news 2.11.14.  NNTP 1.3c is used to
	  transfer almost all news. ]

	I'd like to know if anyone has any ideas on keeping several
news hosts "sync'ed" up so as to allow users to read news on any
machine?

	Specifically, we have 2 seperate news hosts here at USC; our
gateway machine Oberon, and a secondary machine named Nunki.  All
incoming news arrives on Oberon.  Nunki gets all it's news from
Oberon.  There are several hundred machines NFS mounting
/usr/spool/news (the news "lib" directory is also under
/usr/spool/news) from these machines.  Users have the same home
directory on machines which get /usr/spool/news from Oberon or Nunki.

	Currently, a user must either choose to read news on hosts
that get /usr/spool/news from Oberon *or* Nunki.  They cannot just
read news on any old host.  What I'm after is some way of syncronizing
articles between Oberon and Nunki such to the affect that it doesn't
matter what machine /usr/spool/news is mounted from.  To complicate
matters, we'ed like to add 2 or 3 more news machines to ease the load
on the 2 current machines.

	There are several problems that I have thought of.  First is
that there is no way to force an article from news host A to be named
(numbered) the same on news host B.  The best you can do is to
initially copy everything from host A to host B.  Then pray everytime
you transfer an article that it will be numbered the same on host B.

	Another problem is propagation.  Even if we could be assured
that the articles would be named (numbered) appropriately, then you
still have problems in propagating the articles quickly.  Suppose
someone reads news from Oberon's /usr/spool/news.  Since Oberon gets
news almost constantly (NNTP and the ARPANET make a great pair!),
Nunki is always going to be behind.  A few minutes after the user
finishes reading news, he/she moves to a host who has Nunki's
/usr/spool/news mounted.  They read news and find nothing new.  There
.newsrc has now been "fixed" up.  The next time the user reads news
from Nunki's /usr/spool/news, they have to re-read all the articles
that came in to Oberon and weren't on Nunki when they read news on
Nunki.

	We currently NNTP everything from Oberon to Nunki.  I could
crank up the number of "polls" to Nunki to every 15 minutes or so.
This still leaves a large enough window for significant problems.  A
possible solution would be to crank up a nntp xmit everytime an
article for Nunki arrived on Oberon.  But there is just too much
overhead involved (Oberon's only a VAX 750).

	If anybody has any suggestions or experience with what I have
outlined, I would really like to hear from you.


-- 
Michael A. Cooper, University Computing Services, U of Southern California
  UUCP: {sdcrdcf, cit-vax}!oberon!mcooper   BITNET: mcooper@kylara
  ARPA: mcooper@oberon.USC.EDU              PHONE: (213) 743-2957