Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.stecf.org/conferences/adass/adassVII/reprints/schallers.ps.gz Äàòà èçìåíåíèÿ: Mon Jun 12 18:51:49 2006 Äàòà èíäåêñèðîâàíèÿ: Tue Oct 2 04:06:30 2012 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: ï ï ð ñ ñ ð ð ï ï ð ð ñ ð ñ

Astronomical Data Analysis Software and Systems VII
ASP Conference Series, Vol. 145, 1998
R. Albrecht, R. N. Hook and H. A. Bushouse, e
Ö Copyright 1998 Astronomical Society of the Pacific. All rights reserved.
ds.
Cost­E#ective System Management
Skip Schaller
Steward Observatory, University of Arizona, Tucson, AZ 85721
Abstract. Quality system management of computer workstations for as­
tronomy can be achieved with relatively small manpower requirements, if
the right cost­e#ective administrative design decisions are made. Recent
dramatic changes in the price/performance ratio of computer hardware
have modified the model used to distribute computer resources and espe­
cially the usage of the network.
1. Introduction
As part of my duties, I manage the Steward Observatory Computer Support
Group. Our small group provides programming services to several observatory
projects, as well as system administration services for a large number of hosts on
our network. We provide full support for approximately 100 Sun workstations,
70 X terminals, 40 network printers, 40 VxWorks real­time computers, and 20
networking boxes, such as routers, switches, and terminal servers. In addition,
we provide limited support for some 400 other hosts, which are mostly PCs.
Most of these 670 hosts are located in our main building on campus, which has
over 200 o#ces, but others are located in a lab on the other side of campus, and
at four di#erent mountain­top observatory sites. This is all done with essentially
one system manager.
2. What is Quality System Management?
Despite such a thin sta# for such a large responsibility, I am told that the
quality of our system management is second to none, by those who have had
the opportunity to compare with other places. How does this quality manifest
itself? Reliability is one of the best indicators. Our users enjoy 99.9 percent
up time on our systems. Interdependence is minimized. The system is designed
so that one doesn't depend on four or more hosts, (such as a software server,
cpu server, data file server, font server, etc.) to get work done. Another good
indicator is that the systems work as advertised. The mail always goes through.
Software is not installed on the system in a non­functional or semi­functional
form. Users are provided with a default environment that hides gory computer
system and network details, so that they can get right to their job or science
application. This environment appears the same everywhere on the network.
Finally, users get a prompt response to their questions and problems.
139

140 Schaller
3. A Few Good Men
So, how do we accomplish all this? The first thing to do is to hire the right
people. In our university environment, we are often pressured to hire students.
However, our experience has generally shown that even though one can hire
several students for the same money as one highly experienced computer pro­
fessional, the professional will produce more useful work than all the students
combined. A person that is less than 25 years old just doesn't compare with a
person that has more than 25 years of experience. Quality outweighs quantity.
4. Homogeneity
Certainly, another way to maximize the useful work produced by a system man­
ager is to make everything, hardware and software, as homogeneous as possible.
Several more instances of identical workstations require much less extra work
to maintain, than several, even similar workstations that each need to be indi­
vidually custom­tailored. Reducing the number of degrees of freedom, or the
number of variables to deal with, reduces the overall work load. The secret is in
choosing exactly which degrees of freedom to eliminate so that the load on the
system manager is lightened, without seriously inconveniencing the users. The
choice of which variables to eliminate is made by determining which ones are the
most burdensome to administer and least useful to the user. This determination
is based on experience.
5. Just Say No
How do we achieve this homogeneity? A large part of my job is to just say
no. When a user asks me to support a certain hardware or software item, I
must determine its money or manpower cost to our group. If the item is just
another instance of something we already have or do, then the incremental cost
is usually very low, and I can say yes. If the item is new or di#erent, the cost is
usually much greater, and if it doesn't fit into my money or manpower budget, I
must say no. With a fixed amount of money or manpower resources, supporting
a more widely varied list of hardware or software items will reduce the quality
of support for those items already on the list. Why have more alternatives to
choose from, if that means that fewer or none of them will work very well? Why
go to a restaurant that has a very long list of meals on its menu, if none of
them taste very good. In the long term, most users will understand that quality
outweighs quantity.
6. Trends in Technology
Finally, keeping up with trends in technology is another way to reduce the cost
of system management. One important trend currently happening is the rapid
decrease in the price of ether switches. Steward Observatory has just recently
changed over from a routed net to a switched net. This has given us more
e#ective bandwidth, reduced the cost of spares since switches are cheaper than

Cost­e#ective System Management 141
routers, and has reduced the administrative burden, because switches are easier
to manage than routers and because there is now only one subnet to deal with
instead of many.
The other important trend is the rapid decrease in the price/performance
ratio of CPUs, memory, disks, and tape drives, and the fact that networking,
while improving, is not keeping up with the improvements in the other areas.
This is leading us to a server­less model of distribution of computer resources.
A server that exports software to many clients is no longer necessary when the
client can hold all the software it needs on 200 dollars worth of disk space. A tape
server is no longer needed when tape drives are so inexpensive and every client
can a#ord one. Not only the purchase and administrative costs of the server
are saved, but also the cost of making the underlying network carry that load.
The o#ce desk­top workstation soon adopts the model of a home computer, an
autonomous machine that has all the resources it needs attached locally.