Questions and Answers
Before we go to the questions in this issue, let's look
a number of upcoming events of interest to system administrators.
The most important of these is the USENIX LISA VI conference,
will take place in Long Beach, CA, October 19th through
If your budget will allow you only one conference trip
for this year,
this is the one.
The chair of the LISA VI conference is Trent Hein (firstname.lastname@example.org)
from XOR Computer Systems. Steve Simmons (email@example.com)
handling the alternate tracks, and Arch Mott (firstname.lastname@example.org)
is coordinating the BOFs. There will also be a vendor
information about this, contact John Donnelly (email@example.com).
In previous years LISA has targeted large installations.
however, the scope of the conference is being extended
system administrators from all UNIX sites. To get more
please contact Trent Hein or the USENIX Conference office
588-8649. You can also reach the USENIX Conference Coordinator,
DesHarnais, by e-mail at firstname.lastname@example.org.
This year, for the first time, there will be two system
conferences. The other conference (actually the first,
is the 1992 World Conference on System Administration
scheduled for July 20 - 23, in Washington, DC. Since
this is a
new conference, I have very little information about
my impression is that it is targeted toward government
For more information, contact the conference chair,
Alan Paller (email@example.com).
A third conference is the USENIX UNIX Security Symposium,
take place in Baltimore, September 14 - 16. The chair
DeHart from CERT (Computer Emergency Response Team),
who can be reached
at (412) 268-6179 or by e-mail at firstname.lastname@example.org.
can also be obtained from the USENIX Conference Office
Finally, there will be a LISA VII conference next year,
to be chaired
by yours truly. Ideas and requests for this conference
can be e-mailed
And now to something completely different...
Until recently we have been using Suns exclusively.
however, other machines have been introduced. This is
a problem, as
we rely heavily on NIS. Do you know of any public implementation
To my knowledge, no such thing exists. Moreover, my
with NIS's from vendors other than Sun Microsystems
they do not work as well as could be desired. I recommend
the exception of the password file, you use rdist to
the files now serviced through NIS. Depending on how
you have set
up your site, this could generate less network traffic
than NIS, and
it will eliminate some of the less desirable side effects
rdist is a program that distributes files to remote
It differs from other file distribution programs, such
primarily in that it is driven by a control file and
that it updates
the remote file only if the file is out of date. When
you use rdist
to distribute system configuration files, local copies
of the file
are kept on each system. This eliminates network traffic
and provides you with an easy way of ensuring that the
sign is not in hosts.equiv. Of course, if you change
configuration files frequently, the network traffic
required for updating
these files could rise above the level required to run
NIS. In my
experience, however, that this has rarely been the case.
need to decide how often you want to perform the file
for my purposes an hourly distribution has worked well
for files of
Unlike NIS, rdist can be used to distribute any type
including program files. rdist also has a command option
allows directories to be kept as exact copies of the
this option is used, files deleted on the master will
be deleted on the rdist slaves. These two capabilities
be used, for example, to keep /usr/local identical across
As mentioned earlier, rdist cannot be used to distribute
password file, because this file, in a non-NIS environment,
on the local machine. If a password file were to be
rdist, any password change a user had made would be
the years, several solutions to this problem have appeared.
is ACMaint, by David Curry (email@example.com). A description
of this package appears in the LISA IV proceedings.
If you are unable
to borrow the proceedings from a friend, or from your
library, you can purchase it from the USENIX conference
How do I make changes to the /etc/exports file take
As root, type
I am looking for a good network-wide backup program.
Over the years I have seen many such backup programs,
their most common characteristic being that they do
not work. The
two basic requirements for a backup program are (1)
that it work well
all the time, and, especially, (2) that it perform appropriate
when something goes wrong. Therefore, for anything much
a home computer, if the standard UNIX dump (or cpio
if your box is brain-damaged and does not have dump)
do, I would recommend a commercial backup program.
There are currently three packages available which amount
than just a replacement for an existing UNIX command
or a front-end
shell script to tar. These are the Legato Networker,
for System Center, and Budtools from Delta Microsystems.
The Legato Networker uses its own proprietary archive
results in better performance, but creates problems
for the system
administrator. The improved performance will do you
no good if you
are unable to reclaim the data from the tape -- if,
the archive indexes have been damaged (a situation I
with this product). In addition, the "touch and
feel" of the
graphical user interface is MacIntosh-like and, therefore,
to me as an experienced UNIX system administrator.
The other two products, BackupNet and Budtools, have
graphical user interfaces, but are very different in
design and in their licensing structure. BackupUNet,
like Legato Networker,
uses a proprietary backup program, but the archive format
to the tape is that of a standard UNIX utility (tar),
allows for a fallback to a manual restore using that
utility if the
tape index is lost or damaged. Budtools uses the existing
(dump, tar, cpio) and can easily be extended
to any other backup utility, such as GNUtar.
You must do your own evaluation of these three products
in order to
find the one that fits your requirements best. I strongly
that, as part of the evaluation, you run Elizabeth Zwicky's
Torture test. This test does awful things to your backup
has found bugs in every backup utility it has been tested
on so far
(including my old friend dump). Be forewarned: do this
on a machine that can be allowed to crash on a regular
only on a file system you do not mind subjecting to
A paper describing this test and the findings for various
on a number of vendor platforms can be found in the
LISA V conference
proceedings from last year. The test program is available
ftp from ftp.erg.sri.com. Elizabeth can be reached by
e-mail at firstname.lastname@example.org.
About the Author
Bjorn Satdeva is the president of /sys/admin, inc.,
firm which specializes in large installation system
Bjorn is also co-founder and former president of Bay-LISA,
a San Francisco
Bay Area user's group for system administrators of large
can be contacted at /sys/admin, inc., 2787 Moorpark
Ave., San Jose,
CA 95128; electronically at email@example.com; or by
at (408) 241-3111.