Questions and Answers
I need to start by completing some unfinished business.
In the November/December
1992 issue (vol.1, no.4) I explained how to use Archie.
did not mention which password to use. There is a good
this, as Archie does not require a password -- just
log in on the
server as Archie, and you are in business.
Sun User Group
In December, the Sun User Group held its trade show
in San Jose, California. I visited the show floor briefly,
not see much in the way of interesting new hardware
or software. The
exception was a fast Terra Byte tape archive from Metrum
Storage presented by Highland Digital. Unlike existing
which use Exabyte or DAT tape drives, this server is
based on drives
that use large tape formats (they looked like VHS video
provide a much greater transfer rate than an Exabyte
drive. At the
time of the show, there was no software to make this
useful, but I was told that several vendors who have
on the market were in the process of evaluating the
USL Bought by Novell
It has been reported that AT&T has sold its shares
in UNIX System
Laboratories (USL) to Novell, though the sale must still
by the stockholders of the two companies. It is far
too early to speculate
on what effect this development will have on UNIX System
4 in the future, but one may hope that it will result
in a much needed
boost in software quality. One may further hope that
the silly lawsuit
against UC Berkeley and BSDI will be dropped.
And now to this month's questions.
Our organization is preparing to overhaul its news
and there has been a lot of discussion about which news
should be using. We wonder if you have any thoughts
on the subject.
News software consists of two separate and distinct
the news delivery agent and the news reader.
There are a number of news delivery agents, the oldest
which is still used in many installations. B-News is
easiest to install in a vanilla configuration but, because
complexity can be difficult to troubleshoot if it is
used in an unusual
configuration. A newer delivery agent is C-News, which,
some ways still a bit rough around the edges, nevertheless
a significantly better performance than does B-News.
If you are connected
to the Internet, there is a new delivery system available;
INN, and it uses nntp (News Network Transfer Protocol).
choice has been to use C-News, and we have just completed
the newest version, the C-News performance release (which
to my knowledge
has no version number).
There are a number of basic design issues you must consider
your news system. If your users will be reading news
from more than
one host, you will need to make it available on every
host where a
user might want to read news (or at least on a reasonable
such hosts, as, for example, all file servers). There
are two ways
to do this (apart from the traditional USENET transport,
out of the question because of low performance): you
can either NFS-mount
the directory to all hosts supporting the news, or you
can use nntp
to connect to a single news server. C-News will support
while B-News would not, (at least not when I stopped
using it a few
If you are NFS-mounting the news directory, then your
will work almost as if it had been installed directly
on the news
server (with a bit of complication in posting the news).
if your news reader supports nntp, you will not need
mounts. Most modern news reader will support both NFS-mounting
nntp; however, if you have more than a few systems,
that you go with the nntp scheme. Some of the available
reader which can use nntp are trn and nn (and
on a larger site you will probably have to support both,
want the news reader they are familiar with).
Another issue you will need to consider is the growing
volume of news
articles. If you want a full newsfeed, not only will
you need a large
capacity disk (500Mb or more), but within a a few years
you will no
longer be able to receive a day's news using a high
speed within a
24-hour period. (This is amusing to me, considering
that the first
USENET connection I set up in the early 1980s was able
a full newsfeed, using a 1200-baud modem, in just two
hours. A sign
of progress maybe?
Further information about nntp can be found in rfc977.
The GNU people also offer some news software; however,
I have never
used it, and do not know much about it.
How many users can a system administrator support?
It depends on the skill level of the users, and the
of required support. Sites differ greatly, not only
between but also
within such categories as educational or commercial.
Users who need a lot of support will require additional
Support at a high level for an extended period of time
-- say 7:00
AM to 9:00 PM seven days a week -- would require
several people. On the other hand, if users can solve
on their own, fewer people will be needed. At one extreme,
supported a site consisting of 24 file servers and a
little over 300
workstations singlehandedly for about three months.
This was OK for
a short period of time, but did not leave much time
for user support.
Rob Kolstad (kolstad@bsdi,com) has been collecting data
the size of the user populations system administrators
in various settings. This data has been posted to USENET,
but if you
send him e-mail, he will properly be willing to send
you a copy. The
material is very interesting, as it shows very large
the user-to-administration ratios found in real life.
In my judgement, a reasonable ratio in most cases would
like five system administrators per one hundred users,
for very large installations (if run properly, a large
can be more efficient than a smaller one).
At our site we use the automounter to mount the users'
home directories. As a result, the mechanism for naming
home directories is somewhat messy and unsystematic.
How can we improve
In addition to the symbolic links already used by the
automounter, you can add one more level of indirection,
in the form
of a symbolic link from /user/<username> to where
the user's home
directory exists on that machine (through the automounter
or on the home machine, directly to where the directory
is hard mounted).
This will allow users and programs always to refer to
a user's home
directory as /user/<username>. Since this method
of where and how the user's home directory is mounted,
not only gives
users the advantage of a consistent naming scheme, but
the system administrator the advantages of being able
to move users
from one machine to another in a manner that is (almost)
The drawback to this method is that, in order for it
to work well,
you will need to write a shell or Perl script that creates
to a central table maintained by the system administrator.
the links will, over time, become incorrect (and different
to machine), which in turn will cause serious login
In a paper delivered at the LISA V conference, Arch
in much more detail a similar method used at MIPS Computer
Arch can be reached by e-mail at firstname.lastname@example.org.
About the Author
Bjorn Satdeva -- email: email@example.com /sys/admin,
inc. The Unix
System Management Experts (408) 241 3111 Send requests
to the SysAdmin
mailing list to firstname.lastname@example.org