OS selection - Computer Engineering Department

obtainablerabbiData Management

Jan 31, 2013 (5 years and 5 months ago)


Internet Engineering

OS selection

Servers vs. Desktop Systems


Should not contain functionality not required for the intended

Minimal service set

Don’t install anything unless you really need it

Avoid unnecessary exposure to new risks

Faster with redundant components

Increased reliability

Has more of everything

Much more customizable

To perform specific tasks and optimizing them to do so

Administration and maintenance requires special training

Security, Reliability, Stability and … are highly critical

Standardizing on a single OS for all purposes is not a goal!

Operating Systems we will study


Microsoft Windows Server family



OpenBSD from BSD family

There are many others that we do not study here

Other variants of UNIX

Solaris, HP/UX, AIX

Other variants in BSD category

FreeBSD, NetBSD, …

Other variants in GNU category

GNU/Hurd, GNU/Mach, …

And so many other OSs out there

Evaluation criteria


Stability and Reliability




Staff Issues

Total Cost of Ownership (TCO)


OS must support the application you will run!

e.g. Exchange Server

OS = Windows

A constraint for choosing OS

If needs are identified but no specific product

Look for the product and OS that supports it side by side

You are not limited to some specific OSs.

Will not result in an OS that is difficult to support or costly.

Less diversity in OSs is desirable (standardizing server OSs)

For selecting OS

Look at what is generally available on the platform.

What is included in the OS by default?

Applications cont.

Supplementary applications

Intended to supplement a function of OS

Resource Kit/Support Tools for Microsoft Windows

Unix tools for windows

Native OS completeness

There are no functions that an administrator (skilled in
Perl/shell scripting) cannot do in UNIX systems

Windows administrators have difficulty doing management
tasks without third party or supplementary utilities

OS vendor is not supposed to support third party utilities and the
side effects they may have!

Applications cont.

Niche Area Support

Greater diversity of applications available on Windows

Windows is great from this point of view

Diversity in Windows and Linux family

Specific products may not run across the entire family

Enough high quality server products for Linux

Newer system now necessarily backward compatibe


A lot less third party products than either Windows or Linux

Includes compatibility modes with several OSs

It should not be used extensively (e.g. Many Linux applications

OS should be Linux)

Applications cont.

Application Integration

Difference between integrated and integrable!

Features of Microsoft products works better with/only with
Microsoft products!

Usage of one Microsoft product will lead to use of other
Microsoft products

Less tension to be compliant with other products.

Their implementations are not fully compliant with standards and
therefore other implementations.

Other products should try to be integrable!

Application support

Windows is the best, Linux is second and OpenBSD is third.

Applications cont.

Market Products

Small vendors cannot afford to support various OSs

They are pulled towards Windows Server family

Cause: Growth of various Windows based market applications

Windows NT started with a target bellow the high
commercial UNIX systems

Enhancements in each release

Higher performance market

Reducing costs of an application

Major advantage for small businesses

Linux entering the server market

Linux will be a more obvious choice for small businesses.

Applications cont.

Included With Core OS


File and print services, DNS, DHCP, IIS, FTP and other
additional components

Linux and OpenBSD

Includes much more standard Internet servers

Even support for Microsoft file and print sharing

As open source operating systems are free, one might say
that any free software that runs on the OS is part of it.

Applications cont.

open source Applications

Majority of these projects have been developed on Linux

Unless they are platform neutral, they’ll run on Linux with less
effort than any other OS

Microsoft repeatedly made system design decisions that

Make little or no technical sense, but make excellent business
sense, i.e. they make it more difficult and expensive for a
developer to port a Windows application to other OSs.

open source is by no means a UNIX only phenomena, but

Most open source development has been done on UNIX systems

With the UNIX like open source operating systems, Linux and
BSD family, playing the leading roles

Applications cont.

open source Applications

Some open source applications (visit www.sourceforge.net)




PHP, Perl, Python

Web traffic analysis packages like Webalizer, Analog

MySQL, PostgreSQL

Snort, PF, IP Filters, GuardDog



OpenOffice (replacement for Microsoft Office Suite)

GIMP (replacement for Adobe Photoshop)

Applications cont.

OS Versions and Fragmentation

Every several years, Microsoft introduces a fundamentally
different operating environment or system with major
changes in the UI.

Windows is designed to hide technical details, but these
changes introduces a major learning curve!

Technical users may effectively loose a significant part of their
knowledge of how Windows works and need start over with
the new system

These differences are mostly seamless from one version of
UNIX to another

Applications (Summary)

There are many more applications for Windows

Not all needed functionalities are included in the OS

Enough products available for the cost of the OS that
some businesses can run mostly on open source

As Linux is eating into Windows server market share,
expect the application advantage for Windows servers to
shrink and perhaps disappear.

Maintaining an application for Linux and other UNIX
variants is minor compared to UNIX and Windows.

Reliability and Stability

Both are related to bugs.


Relative resistance to crashes and lessening their affects

Bugs and incompatibilities may cause crashes


Specific functions stop responding or return invalid results

Odd behavior!


Affected by thing related to reliability and stability

To do and keep doing what they are supposed to do

Least possible amount of time staff spend troubleshooting

Reliability and Stability cont.

Reboot required even for minor changes

Microsoft’s origins in single user systems

Is not a part of UNIX or mainframe environments

Some systems become less stable for longer uptimes

Rarely necessary for UNIX systems

Windows flaws in architectural design

Windows registry

Incredibly confused directory structure and its adverse
impact on system recovery

System management functions contained in large complex
GUI programs mostly with no command
line counterparts

Reliability and Stability cont.

Windows registry

Central repository for configuration data and …

The fallacy is that registry data is accessed by key name.

Little fundamental difference between accessing entries in
registry and files in different directories with different filenames

Numerous binary tree lookups, in a large deeply nested
structure, become quite resource intensive

Confirmed by the fact that Windows systems slow with age as
software is added

UNIX systems do not slow with age due to software installs.

Reliability and Stability cont.

Windows GUI Interface Hampers Administrators

Complex GUIs contributes to reliability issues

Such programs are harder to write and more likely to have
their own bugs

Often, no alternative interface is provided

Bug in management interface will result in inability to perform
some administrative tasks

In the UNIX world, essentially all administrative tasks are
performed by relatively simple command line programs
that do only one specific thing.

Reliability and Stability cont.

Linux Stability

There is no need to ever reboot except for a kernel or
hardware upgrade or change.

Registry problem is not applicable to Linux


Said to be the most stable and most reliable OS

Clean code base

Development model


File Systems

FAT lacks primary permissions and security facilities
needed for a server environment.

UNIX allows controls only by owner, group and other. Each
of these can be set to any combination of read, write and


NTFS is much more customizable and provides flexible
access control list capabilities.

Windows GUI, xcacls provided in Windows Support Tools

Security cont.

Password Hashes

Windows passwords are weaker and easier to break.


BSD MD5 is one of the strongest hashes

Novice administrators really don’t know what they are
doing! Making things easy is not that good!

Default Installations

Previously default installation of Windows Server and
related network services made it much more easier to
attack and exposed the system to many risks.

Unix default installation has basic security provisions.

You have to enable anything you want.

Security cont.

Development Model, Bug Fixes, Security and Reliability


The kernel appears to be under pretty much continuous
development and more than one version is being developed

Development is a purely volunteer, non
commercial activity.


Microsoft is the largest software company in the world and is
purely commercial.

Microsoft responds in a reasonably timely fashion to reported
and serious security bugs. It's primarily such bugs that their
security alerts describe.

Security cont.


OpenBSD is the most secure OS available

They try to find simple software bugs and they believe that
they are the origin of security issue.

Secure by default

All non
essential services are disable by default

Four years without a remote hole

Outstanding open implementation of security standards.

Unix Signal Handler and Open Software Fixes

Fix was available the day after the problem was announced

OpenBSD Daily Security Audit enabled by default



How many processors/How much memory in a single
machine, an operating system is capable of supporting.

Cluster of machines that work together to solve a common

Recent projects of this type have consisted of hundreds to
thousands of Intel CPUs running Linux.

System Performance

Confusing benchmarks about performance.

No general statement on this issue.

Scalability cont.

Hardware Requirements

Windows has GUI in its kernel

It need reasonably high hardware specifications.

Most Linux servers installations do not have X

Hardware specifications of Linux is much smaller than

Price Performance Ratio

The starting software cost for a public, Windows 2000 web
server, is effectively over $4000.

There exists free Linux distributions and also commercial
ones which costs much less than Windows servers

Scalability cont.

Relocating Server Applications

Deep understanding of server status will result in wise
decision on relocating server applications.

Decision support

Windows’ Task Manager or Performance Monitor

UNIX’s ps command or Performance Analyzers like atop

Duplicated UNIX machines do not need to be kept as
replicas. Application server load can be broken up between
two machines.

Duplication and Load Balancing

Highly modular and so highly customizable

Migrating Windows functions nearly always means building
new machines from scratch. Difficult to duplicate the settings!


Ease of Use ≠ Ease of Learning

Ease of use often regarded as one of the most important
characteristics of any software product.

Ease of learning is not often used.

Ease of use is nearly always used to mean that a product is
easy to learn to use.

Normally means how easily a user new to a product can figure
out how to perform a specific action.

Documentation, architecture, support, training and design

GUI tools

May also make system administration tasks easy to learn.

May make repetitive task very burdensome

Such tasks can make use of a system scheduler.

Usability cont.

Windows Lacks Automation

Automating the task in Linux by scripts

In Windows also possible but is very cumbersome in
comparison with Linux

Automating the procedures that has no counterpart other than
GUI interface should be done with e.g. emulating mouse
events or scripting utilities like AutoIt that does somehow ease
this job! (Surely not reliable)

Easy to use learn Windows tools, become cumbersome to use
as the tasks become more repetitive.

There are no scripting skills that are routine part of
Windows administration

Even batch programming skills, as simple (and limited) as that
"language" is, have largely fallen into disuse.

Usability cont.

Most Windows administrators are entirely dependent on the
GUI management interface, and even where it should be
obvious that something should be automated, do not have
the knowledge or skills to do it.

UNIX administrators, in contrast, are normally skilled in at
least one scripting language, and routinely expect to
automate repetitive parts of their jobs.

Windows server systems have a pro novice bias and that
UNIX systems have an anti
novice bias.

Usability cont.

Support Options


Microsoft Knowledge Base, Customer Support, Consultants

Most of the things are solved easily if you have employed a guru
consultant. The really good ones can solve seemingly very difficult
problems, with ease

Gurus are expensive to employ and cheap ones learn on your job.


Community Support, Commercial Support (e.g. RHEL), Gurus

After gaining mastery and enough experience your are relaxed.

It does not hide anything from you, so you can come up with the

Google your problem and there should be a discussion about it in
a community

Staff Issues

UNIX administrators cost more than Windows ones.

Main factor = Cost per machine

From all previous discussions it is resulted that
maintaining a Linux server needs less effort that
Windows one.

So the staff cost is not a major factor as might be
considered at first

Total Cost of Ownership (TCO)

Microsoft says TCO of Windows is much lower than Linux





Windows license price

How many simultaneous client connections?

What server applications?

UNIX systems require more up
front learning effort.

Security, Stability and Reliability

Moving to security, Linux is more secure in a default install

Given normal installs by typically trained administrators Windows
systems are much less stable than Linux installs.


No operating system is perfect or even close, even when
limited to server only or desktop only roles.


Windows servers

With sufficient resources, they can be made stable.

Because of variety of third party applications , it may be
possible to "do more" on Windows servers than other

As a particular matter, they rarely live up to their promise.

Contain enormous array of unused features (may not be
easy to disable, for instance kernel customization).

Summary cont.

Comparatively unreliable, and thus resource intensive to

Theoretically, they can be made secure, as their built
security functions are more sophisticated than standard
UNIX security facilities.

Very labor intensive and will result in a machine that will not
look like a Windows server.

Given the complexity of Windows, tools and middleware
used to build the applications, and the applications
themselves, it's absurd to think that all the security related
bugs can be found and fixed.

Only hope that the holes that exist are sufficiently difficult and
obscure, that no skilled malicious intruder actually finds them.

Best hardware support among other OSs.

Summary cont.


The default security characteristics of Linux depend on the
distribution and install options chosen.

Linux has been used to build powerful parallel supercomputers
so it unquestionably clusters well

The newest kernels should be comparable to Windows on
multiprocessor systems.

Linux has a very large range of applications, both commercial
(proprietary) and open source.

Linux has by far the largest number of open source applications.

All business needs can be met by Linux applications.

Linux has the best and most diverse free support available, which
is often better than traditional commercial support.

Choosing a Linux Distribution

Some server candidates


Red Hat Enterprise Linux

SUSE Linux Enterprise Server

Mandriva Corporate Server







Choosing a Linux Distribution cont.


Base operating system

Some customization, e.g. init scripts, kernel

Generally binary compatible

Software management and updating





Hardware management

Kudzu of Red Hat

commercial distros never contain proprietary drivers.

Proprietary extras

Choosing a Linux Distribution cont.

Support from server manufacturers mainly

Red Hat Enterprise Linux

SUSE Linux Enterprise Server






Choosing a Linux Distribution cont.

Red Hat

Founded in 1994 by Bob Young and Marc Ewing

Leader in development, deployment and Management of Linux
and open source solutions for Internet infrastructure

Last version in the Red Hat Linux product line

Red Hat Linux 9

Replaced by Fedora Core in late 2003, officially sponsored by Red

Developed with community participation

Has a short life

Serves mainly as a testing base for Red Hat Enterprise Linux

Widely used, excellent community support, lots of innovation

up2date and YUM as package managers (RPM)

Red Hat Enterprise Linux products best supported by hardware
vendors among other Linux distributions

Very good commercial support

Choosing a Linux Distribution cont.

SUSE (formerly SuSe)

Established by a group of German developers in 1992

Adopted RPM package management format

Easy to use YaST configuration tool

Frequent releases

Excellent documentation

Acquired by Novell in late 2003

Professional attention to detail

YaST (RPM), third
party APT (RPM) repositories available
as package managers

Choosing a Linux Distribution cont.


Created by Daniel Robbins, a former Stampede Linux and FreeBSD

A source
based distribution

Various levels of pre
compiled binary packages to get a basic Linux
system up

The idea is to compile all source packages on the user's computer

Highly optimized for the computer architecture it is built on

Long and tedious system installation

Occasional instability and risk of breakdown

Software packages kept in a central repository

Usually kept highly up
date and available within days

Painless installation of individual software packages

Highly up

Superb documentation

Distribution tailored to user's needs

Portage (SRC) as package manager

Choosing a Linux Distribution cont.


Started by Ian Murdock in 1993

Totally free, completely non

Complete package set (about 16000 packages)

Community support

Most advanced package manager available


Needs knowledgeable, hands
on user

Three release branches


Long period between stable releases

The stable version tends to be out



CE Servers


Fedora core 4

At the time of the new installation of CE, the administration team had not
made decision to move toward Debian, so Fedora was chosen (The team is
willing to change it to Debian)


Debian Sarge


Debian Sarge



Tailored for stable network services we wanted to provide (DHCP, DNS,
Firewall, Mail Queue, …)

Client management server

Windows 2003 Enterprise Edition

For managing Windows clients you have to run Windows!

AntiVirus, Patch Management and Client Management server


Information provided in this presentation are not
accurate and may be out of date.

There are many fundamental changes in Windows
Server 2003 and Linux Kernel 2.6.

Most parts of this presentation are based on Windows NT
and 2000 and Linux Kernel 2.4.

Microsoft tries to provide a better command line interface

Windows Management Instrumentation Command
(WMIC) tool is a great pace! Read about it and try it…

// TODO: Try wmic.

Resource Kit/Support Tools

// TODO: Download Windows Support Tools and try the tools.


GeodSoft: Linux, OpenBSD, Windows Server


Software in Review

The differences between Linux







Origin of code?



Free Software Foundation; kernels developed separately except HURD. The Linux kernel
was originally written by Linus Torvalds, and is currently maintained by him.


FreeBSD, OpenBSD,
NetBSD, DesktopBSD,

UC Berkeley, originally; each project has been developed separately since the early
1990s, however.


Solaris, AIX, IRIX,
HP/UX, Tru64,
UnixWare, OpenServer

Bell Labs (AT&T) developed the original Unix code. UNIX is now a trademarked operating
system certification program instead of an operating system, and no longer requires that a
compliant OS contain AT&T Unix source code to achieve brand certification. Despite that,
all of the extant Unix derivatives are compliant with at least one published UNIX standard.


Darwin, OS X

Based on the NeXTSTEP operating system, which used the Mach kernel and some
FreeBSD programs and networking code. OS X is developed from Darwin.



Originally written by Andrew Tanenbaum, but now mostly developed by a handful of others

Miscellaneous cont.

BSD Family

OpenBSD was an outgrowth of NetBSD

Split later with the goal of creating a reliable and secure OS

OpenBSD is the most secure OS available

NetBSD is known for running on more hardware platforms

FreeBSD split from NetBSD

Developers wanted to optimize the system for perfomance on
Intel processors

Fastest OS that runs on Intel systems