Unix to Linux Migration - An Introduction

UNIX® to Linux® Migration: An IntroductionBy Nathan Thomas

Abstract This paper is intended to provide a discussion of theimportant considerations, best practices, and resources formigrations from a RISCbased platform to Linux. Itpresents the differences between UNIX and Linux andprovides an overview of what to expect when migrating toLinux. The document should serve as a general referenceguide during a typical migration and provide information onadditional Red Hat resources that will assist with theoverall strategy and implementation.

Revision 4a. February 2005

Copyright © 2005 Red Hat, Inc. All rights reserved. “Red Hat” and the “Shadowman” logo are registered trademarks of Red Hat, Inc. in the US and other countries. Linux is aregistered trademark of Linus Torvalds. All other trademarks referenced herein are the trademarks of their respective owners.

Table of ContentsIntroduction........................................................................................................3

What is Red Hat Enterprise Linux?..............................................................3What is open source?...................................................................................4What is Red Hat's business model?............................................................5

Operating system differences............................................................................5Basic UNIX infrastructure.............................................................................5Open source tools .......................................................................................6File system....................................................................................................6Performance.................................................................................................6Stability.........................................................................................................8Scalability......................................................................................................8Security.........................................................................................................9

Enterprise operating environment.....................................................................10Typical Linux usages....................................................................................10IT infrastructure............................................................................................11Desktop.........................................................................................................12ISV application support................................................................................13Largescale Linux deployment.....................................................................13Remote management capabilities ...............................................................14Skills transfer and training............................................................................15Directory and authentication services..........................................................15

Proprietary application porting and development.............................................15A word about the GPL..................................................................................15The Linux development environment: C and C++.......................................16Thirdparty libraries......................................................................................17Red Hat Developer Suite..............................................................................17Specialized porting tools..............................................................................17Java and scripting languages.......................................................................18Software packaging......................................................................................18

Supporting Linux in the enterprise....................................................................18Red Hat Global Support Services................................................................18Global Support Services Technical Account Manager................................19Red Hat Global Professional Services.........................................................19GNUPro enterprise tool support...................................................................20Red Hat Global Learning Services...............................................................20Red Hat Network..........................................................................................20

Migration strategies...........................................................................................21Suggested migration plans and timelines....................................................21

ISV application support......................................................................................23Conclusion.........................................................................................................24

Unix to Linux Migration: An Introduction 2

IntroductionAs enterprise customers have become frustrated with the priceand performance of proprietary UNIX solutions, they havesought a way to take advantage of the multivendor, lowcost,highperformance environment provided by Intel® and AMD®

commodity priced hardware. Historically, the lack of a stable,secure, scalable, and high performance operating environmentrelative to UNIX has kept many customers from being able tojustify a move to commodity chipsets. Even those customerswilling to accept the limitations of the Microsoft® Windows®

operating system running on commodity hardware have faced avery tough migration, porting, and integration effort. Such costand effort pose a significant barrier to entry. UNIX variants havebeen released for commodity platforms, but none of them havebeen able to provide adequate hardware support, softwaresupport, or scalability to make Intel or AMD an effectivealternative to RISCbased platforms. Now, as a product of thecontinual improvement of commodity platforms and the rapiddevelopment of the Linux operating system, there is finally aviable alternative to UNIX for running enterprise and missioncritical applications. Linux is now the fastest growing operatingsystem in the world, according to IDC, and it is most oftenreplacing proprietary UNIX in enterprise IT infrastructure. Thispaper outlines the basic differences between Linux and UNIXand provides information to make informed decisions aboutwhere Linux may replace UNIX in the enterprise today.

What is Red Hat Enterprise Linux?

Prior to the release of Red Hat Enterprise Linux AS 2.1, theLinux marketplace was a very difficult one for IndependentSoftware Vendors (ISVs) in general and database vendors inparticular.

The open source development model has historically beendriven at an extremely rapid pace. For example, in just 18months Red Hat released Red Hat Linux 7.3, 8.0, and 9. Thismodel was vastly different from the much longer release cyclesprevalent in the proprietary operating system space and was notin line with the development models many enterpriseapplications require.

Red Hat developed Red Hat Enterprise Linux as the singletarget platform for all major ISVs and their enterpriselevel serverapplications to alleviate the burden the previous developmentcycle was putting on software development companies. WithRed Hat Enterprise Linux, Red Hat provides a platform that bothISVs and system administrators can support. Red Hat EnterpriseLinux AS 2.1 first became available in May 2002. Red Hat alsoreleased Red Hat Enterprise Linux ES and Red Hat EnterpriseLinux WS shortly thereafter to complete the product line withdistributions appropriate for midrange server applications andtechnical workstations. Red Hat Enterprise Linux is released


approximately every 18 months, giving ISVs more time to certifyand deliver their products and see a return on their investment.Subsequent releases of Red Hat Enterprise Linux, version 3 andversion 4, were released in October 2003 and February 2005.All versions of Red Hat Enterprise Linux are maintained by RedHat for seven years after the initial availability date. Red HatEnterprise Linux products are available to customers throughannual subscriptions, which include maintenance, support, andupgrades.

Red Hat Enterprise Linux is a more focused environment thanthe old retail Red Hat Linux products or the communitydrivenFedora Project. The Red Hat Linux product line is no longeravailable or maintained by Red Hat, while the Fedora Projectpicked up where Red Hat Linux development left off. The FedoraProject is an endeavor through which Red Hat works with theopen source development community to build, test, andeventually integrate software into its official releases. Softwarepackages the community tests and deems stable will likelyundergo extensive internal QA and become part of Red HatEnterprise Linux. While the Fedora Project provides a variety oftechnologies and applications that are either not businessrelated or are still in the process of development, Red HatEnterprise Linux packages are selected for their stability andapplicability to a production enterprise environment.

The longer release cycle for Red Hat Enterprise Linux does notmean that system administrators must sacrifice the timelyrelease of security and bug fix updates they have come toexpect from Red Hat. Bug fixes and security updates arereleased on an asneeded basis to ensure that customers havethe most reliable, stable, and secure systems possible. Theseupdates are made available through Red Hat Network, whichenables the easy deployment of updated software to a largenumber of systems. The intent of Red Hat Network is to reduceadministrative overhead for corporate system administrators bysimplifying and centralizing package management and systemmaintenance at an affordable cost.

More information on the current Red Hat Enterprise Linuxproduct line is available at http://www.redhat.com/software/rhel/.

What is open source?

The term open source refers to the practice of distributing thesource code of an application as well as the binary (compiled)version. This allows the user to make modifications to the codeand improve it any way they see fit. Red Hat is firmly committedto open source because it allows a level of innovation that is lightyears ahead of the proprietary software development model.With thousands of programmers able to contribute to theoperating system, including developers and systemadministrators inside our enterprise customer accounts, Red Hatis able to facilitate rapid enhancements in functionality,


performance, reliability, and security that take proprietaryvendors years to achieve. There are a number of popular opensource licenses, including the GNU General Public License andthe BSD License. While some proprietary software vendors haveattempted to position open source licensing as an inhibitor toinnovation and application delivery, such criticisms distort themeaning of the open source licenses and exaggerate theinstances in which the GPL impacts the licensing schemeadopted by application vendors. In the overwhelming majority ofcases, such as the Oracle database, vendors successfullysupport their applications on Red Hat Enterprise Linux under theproprietary licensing model familiar on Windows and UNIX. Thesection of this paper entitled “Proprietary Applications Portingand Development” clarifies the impact that open source licensesin Red Hat Enterprise Linux have on the licensing of software.

What is Red Hat's business model?

Red Hat has built a profitable business with open sourcesoftware. Red Hat's business plan is to derive the majority of itsrevenue from subscriptions associated with the development,integration, deployment, support, and management of Linux inenterprise environments. Additionally, Red Hat works with manyISV and OEM partners to ensure that Red Hat Enterprise Linuxproducts enjoy the widest level of application and hardwarecertifications of any enterprisefocused Linux distribution.

The latest market analysis indicates that the line betweensoftware and softwarerelated services is blurring as aconsequence of the high degree of connectivity of today'ssystems. Additional information on the full range of servicesprovided by Red Hat is included in the section of this paperentitled, “Supporting Linux in the Enterprise.”

Operating system differencesAlthough Linux is basically a UNIXlike operating system, thereare a number of subtle differences between Linux and UNIX.Few of these differences have a significant impact on the enduser experience or application functionality, but it is important tounderstand what differentiates Linux from UNIX to helpdetermine where to utilize it in the enterprise.

Basic UNIX infrastructure

With a basic infrastructure similar to UNIX, Red Hat EnterpriseLinux consists of a kernel that handles all hardware and deviceinteraction as well as all job scheduling. Surrounding this kernelare all of the userspace applications, many of which are thesame or similar to those found in the base UNIX installations.Linux can be run in text or graphical mode as with UNIX, and thegraphical mode is supplied by the X.org X Window System.


Like UNIX, Linux comes with a large selection of builtinapplications that combine to provide a high level of standardfunctionality. Tools for working in a networked computingenvironment such as BIND, NFS, FTP, Telnet, SSH, rsh, and anumber of other applications are distributed with the coreoperating system itself.

Open source tools

Unlike UNIX, Red Hat Enterprise Linux is delivered with a hugerepository of open source software that provides complementsto, or direct replacements for, third party ISV applicationsavailable on other operating systems. For many users theseapplications have proved to be acceptable alternatives to someof the tools they have previously had to purchase; others havefelt more comfortable simply using the Linux version of theirexisting ISV applications. Examples of such open sourceapplications include Apache for Web serving, Sendmail for mailtransfer, CVS for source code management, and PHP fordynamic Web applications.

File system

All versions of Red Hat Enterprise Linux use EXT3 as the default for their native file structure, which is the nextgeneration of the EXT2 . EXT3 is a tunable journaling; data migration between EXT2 and EXT3 is seamlessand simple, with backwards and forwards capabilities. Red HatEnterprise Linux v.3 included EXT3 updates for security andstorage management with ACLs and a bundledLogical Volume Manager, while Enterprise Linux v.4 providessignificant performance enhancements with Block Reservations,Hashtree Directories, and improved SMP synchronizationtechniques.

Red Hat also offers customers a clustered file system that canbe purchased to run on Enterprise Linux. Red Hat Global FileSystem (GFS) is a highly stable solution for enterprise andtechnical computing applications requiring reliable access todata. GFS allows multiple servers on a Storage Area Network(SAN) to have read and write access to a single filesystem onshared SAN devices, delivering the strength, safety, andsimplicity demanded by enterprise and technical computingenvironments.

Performance

Red Hat Enterprise Linux is highly optimized to provideexceptional performance on commodity chip sets. Red HatEnterprise Linux has been optimized for enterprise IT operationsand is currently demonstrating worldclass performance in criticalenvironments. Anecdotal evidence from enterprise userssuggests that Red Hat Enterprise Linux running on Intel andAMD chipsets are able to match, and in many cases exceed, the


performance of Solaris™ when running natively compiled C/C++code. Additional optimizations in specific incidences have beenable to achieve 5 to 20 times increases in performance over theapplication performance on UNIX. It is important to recognizethat significantly cheaper commodity hardware makes it possibleto purchase a substantially faster and better equipped systemthan an equivalently priced RISC system, allowing a dramaticleap over RISC hardware in cost/performance. Such statements,however, are directed only at raw processing performance. Interms of I/O and network throughput, evidence suggests thatRISC and commodity architectures are closer to parity. Fiberattached storage reads, for example, will not usually benoticeably faster on Linux than on UNIX. Again, this implicitlygives Linux a cost/performance edge because of the lowhardware cost. In certain networking circumstances Linux is ableto beat UNIX performance, although more at the applicationlevel than in terms of raw TCP/IP or UDP throughputcapabilities.

Red Hat Enterprise Linux is achieving outstanding industrystandard benchmark results that can be used to assesscapabilities across the entire product line. The results cover arange of configurations, architectures, and performance metrics.Red Hat Enterprise Linux has been a core part of configurationsthat offer significant performance and cost advantages overtraditional RISC/UNIX environments.

The Transaction Processing Performance Council Benchmark C(TPCC) has become a highly regarded industry reference thatmeasures online transaction processing and databasebenchmarks. As of October 2004 Red Hat Enterprise Linux heldthe worldrecord TPCC performance benchmark result. Theaudited figures were 1,184,893.38 tpmC at $5.52/tpmC. Thisresult beat the previous performance record, achieved by RedHat Enterprise Linux 2.1, by approximately 17% and was thelowest $/tpmC of the first ten performance results. The results ofthis benchmark demonstrate that Red Hat Enterprise Linux withOracle in a clustered environment can be up to 50% faster thanthe best Windows 2003 result and 98% faster than the bestSolaris result.

The benchmark was achieved with Red Hat Enterprise Linuxrunning on a 16node HP Integrity rx5670 Itanium cluster (eachnode being quad CPU with 48GB memory). The database wasOracle 10g with Real Application Clusters. The storagecomprised over 2000 disks with a total capacity of 93TB. Theapplication server tier was comprised of 80 dual CPU Xeon HPProLiant DL360G3 systems. The total configuration cost was$6.5M. This benchmark proves the outstanding performance,scalability, and cost effectiveness of Red Hat Enterprise Linux.

Other recently archived Red Hat Enterprise Linux performancebenchmarks can be found at:http://www.redhat.com/software/rhel/benchmarks/


Stability

Red Hat Enterprise Linux has become well known for its stabilityover the past several years. Stories of machines locked inclosets running for years are common, and most users rarelyexperience significant downtime. Much of this can be attributedto the robust architecture of the system itself. The Linux kernel isdesigned to minimize the effect that application components willhave on each other and the kernel with regard to resourceallocation. This means that if single applications fail, they will failin isolation, and leave the rest of the operating system tofunction as expected. But how does a heavily loaded Red HatEnterprise Linux system deployed in an enterprise datacenterenvironment hold up under the the toughest workloads?Research has shown that Red Hat Enterprise Linux holds upvery well indeed, on par with, or better than results for RISCbased systems. The quality assurance measures Red Hatapplies to the operating system prior to release includesignificant testing of high stress operational conditions, and weconsider failures at this level to be unacceptable in a commercialproduction operating system.

Scalability

Linux has proven itself in enterprise environments, andscalability has been a priority for Red Hat engineering. EachRed Hat Enterprise Linux release has offered increasedscalability over its predecessor – with support for larger SMPsystems, more memory, and larger storage subsystems.

Additionally the architectural limits on Linux scalability havesignificantly improved and continue to evolve. Prior to therelease of Red Hat Enterprise Linux, most Linux products werelimited to x86 architectures, which inhibited Linux fromdeveloping as a vertical enterprise solution. Red Hat EnterpriseLinux is available for seven different architectures and can bedeployed on anything from an administrator's laptop to acorporate mainframe. Red Hat's ISV partnerships and OEMrelationships are very strong, with Red Hat Enterprise Linuxgiving customers the ability to build a completely Linuxbasedenterprise infrastructure.

As Red Hat increases its focus on largescale remote systemsmanagement, it is expected that the cost to add nodes in termsof administration will continue to diminish, allowing, in atheoretical sense, unlimited scalability. For those scenarioswhere single box scalability is required, Red Hat EnterpriseLinux solutions built around IBM's S390 and Z Series systemsare also available. In addition, a whole new generation ofdatacenterquality commodity architecture blade solutions fromsuch companies as Egenera, IBM, HP, and Dell have alsopenetrated the market. These platforms deserve a much largerdiscussion than can be provided in this paper and will continueto be an important component of the overall Linux market.


Security

Provision of a highly secure environment is a core feature of theRed Hat Enterprise Linux family of products. Red Hat EnterpriseLinux has fewer serious security vulnerability reports than eitherUNIX or Windows, despite the fact that Red Hat Enterprise Linuxcontains many applications not included in other operatingsystems. While this is not scientific proof of Linux security, it is agood indication of realworld experience for Linux. Red HatEnterprise Linux gives the administrator complete control overnetwork ports and services, and many security andauthentication applications are fully supported, includingKerberos, SSL, NIS, and PAM. Red Hat Enterprise Linuxsecurity updates are available to customers via Red HatNetwork. Red Hat packages are signed with Red Hat's GNUPrivacy Guard (GPG) keys so customers are certain updatesare distributed securely from Red Hat.

Thirdparty firewall applications such as Checkpoint andmonitoring solutions like BMC Patrol are supported and haveproven very stable on Linux. Customers should note thatsecurityrelated products available from ISVs are only certifiedfor the Red Hat Enterprise Linux line of products. Securityapplications modified to run on the Fedora code bases are notsupported by Red Hat or the application vendor.

Red Hat Enterprise Linux has achieved the US DefenseInformation Systems Agency (DISA), Common OperatingEnvironment certification. The COE certification means that RedHat Enterprise Linux is approved for deployment at the USDepartment of Defense and has passed this agency's strictrequirements for interoperability, performance, and standardscompliance, a true testament to the federal governmentsconfidence in Red Hat Enterprise Linux as a sound solution.Customers interested in learning more about the COEcertification should refer to the the Red Hat Enterprise LinuxCOE whitepaper at:

https://www.redhat.com/apps/webform.html?event_type=whitepaper&eid=100

In addition to the applications, management tools, andcertifications associated with providing security on Linux, it isimportant to understand the role of the open sourcedevelopment model in making Red Hat Enterprise Linux secure.Open source means that all of the code that Red Hat runs hasbeen through a large amount of peer review. Open sourcedevelopment also means that new bugs are resolved accuratelyand made available in a timely manner with documentation forthe next round of peer review or future development.

Red Hat Enterprise Linux customers with an interest in tuningtheir systems securely should refer to the Red Hat EnterpriseLinux Security Guide at:


http://www.redhat.com/docs/manuals/enterprise/

Security enhancements for the Red Hat Enterprise Linux v.3product line included Access Control Lists, a generalpurpose cryptographic API in the kernel, and kernel support foripsec on IPV4.

Red Hat Enterprise Linux v.4 includes numerous securityfeatures:

• Security Enhanced Linux (SELinux), which provides a fullytrusted environment, with Mandatory Access Control (MAC)and Role Based Access Control (RBAC)

• A new Auditing subsystem for standard and SELinuxenvironments

• Position Independent Executables and Exec Shield –features that provide protection from Buffer Overflow securityexploits

• Compiler and Library buffer management enhancements –features that perform runtime checking of buffers for errorssuch as double deallocation and buffer size validation

Red Hat provides several whitepapers that discuss thesesecurity features in detail. Please refer to www.redhat.com.

Enterprise operating environmentThose who were involved in the IT industry as Sun and Microsoftbecame the dominant players in their respective markets willrecall what a difficult transition it was to integrate and supportthose new platforms. Recognizing that the barrier to entry forLinux migrations can be high, Red Hat has worked to make theprocess as painless as possible. Below you will find informationon the common tasks that Red Hat Enterprise Linux is beingused for and on how enterprise clients are able to integrateLinux into their environments without having to discard theirexisting infrastructure and knowledge.

Typical Linux usages

Although Linux is a very flexible operating system that is beingused everywhere from embedded devices to mainframes, themajority of enterprise users are deploying Red Hat EnterpriseLinux on commodity 32bit and 64bit Intel and AMD machines inone of three primary configurations: IT infrastructure andinterdepartmental servers, application servers for core businesscomponents, or as a desktop/workstation solution. Red Hat hasalso established itself as a major player in the datacenter fordatabase connectivity and in numerous other areas, such asCAD development and graphics design, but these can be fairlyspecialized solutions. We will focus on the more generaldeployment scenarios here.


IT infrastructure

Red Hat Enterprise Linux has largely made its name in suchapplications as customerfacing ebusiness operations, internalrouting, firewalls, file serving, print serving, interdepartmentaldatabases, and dozens of other standard IT infrastructurefunctions. Here's a quick look at the specific solutions that arecommonly seen; additional information can be found at the endof the document:

Table 1: IT infrastructure

For business applications designed to run on UNIX, the port toRed Hat Enterprise Linux is relatively simple. This includesC/C++ applications, Java applications, scripts, and several otherlegacy or newer languages. Linux was originally conceived of asa server operating system, and it has been configured to workoptimally in that environment. Performance has proved to becomparable to or better than that of UNIX, and scalability andreliability are more than acceptable. So saving money byswitching to Intel or AMD hardware is an easy choice. Additionalinformation on porting applications to Linux is given in Section 4of this document.


Function Details

Web server Apache, TUX

Routing/DNS BIND8/9 Full routing capabilities are supported.

File server

Firewall

NIS server NIS

Mail server

CVS

Web caching Squid

Software Components

Apache is the world's number one Web server. Linux offers a full suite of Web hosting, application hosting, and proxy capabilities. TUX is a threaded Linux Web server for high performance Web serving.

NFSv4 in RHEL 4, openAFS, GFS,

NDS, openLDAP, Samba

Another core area for Red Hat Enterprise Linux; consistent communication with all platform types is one of Red Hat's primary goals.

Iptables Iptables is included free.Simple network lookup service that provides information to all machines on a network.

Database server

Postgres, MySQLPostgres and MySQL are very robust open source databases.

Sendmail, Postfix

Sendmail is the most widely used MTA on the Internet. Postfix is a fast, secure open source MTA alternative to Sendmail.

Source repository

CVS offers a free and widely used repository.Squid is a Web proxy server that ships with Red Hat Enterprise Linux.

Desktop

Traditionally UNIX has not played a major role in the enduserdesktop space. It has been limited to specialized usage within anenterprise for the running of specific business applications,application development, or as a powerful workstationenvironment. Red Hat Desktop and Red Hat Enterprise LinuxWS can act very effectively in these environments, and in manycompanies are being used as a replacement for existingWindows desktop clients. Linux uses the X.org X WindowSystem as its graphical interface, with various desktopenvironments available to provide a consistent user interfaceand all of the baseline tools a desktop OS user expects.Additionally, there are a number of office productivity suites,Web browsers, graphical manipulation tools, and personalproductivity applications available. There are also a number ofISV management tools, such as Oracle Enterprise Manager thatcan now be run from Linux. Table 2 illustrates some of theapplication availability. Note that information on Linux as adevelopment environment is given in detail in Section 4 ratherthan here:

Table 2: Desktop Availability

Red Hat Enterprise Linux desktop features include:

• X.org windowing system

• Bluecurve graphical user interface (Unified GNOME/KDElook and feel)


Function Details

GNOME, KDE

Web browser

Office suite

Software Components

Desktop environment

GNOME is the default desktop in Red Hat Enterprise Linux. It provides all of the basic functions Windows users would expect from a base desktop installation, including file browsing, desktop configuration tools, basic text editors, calculator, etc. Sun has chosen GNOME as their next generation desktop.

Firefox, Mozilla, Konqueror

Firefox is the default browser in Red Hat Enterprise Linux 4. All are free and open source.

OpenOffice.org, Koffice,

StarOffice

OpenOffice.org is a leading commercial office suite for Linux. It includes word processing, spreadsheet, graphical development, slide presentation, and webpage development tools. All three support Microsoft file types.

Messaging client

Evolution, Mozilla,

Thunderbird, text readers

Traditional UNIX mail readers are available.

• OpenOffice.org office productivity suite

• Evolution mail & groupware client

• Firefox & Mozilla Web browsers

• Numerous multimedia applications (HelixPlayer, RealPlayer,etc.)

• Microsoft interoperability features (Active Directoryauthentication, Exchange Server connectivity, NTLMauthentication)

• Microsoft File and Print sharing

ISV application support

One of the biggest challenges Linux has faced moving into theenterprise has been the support of Independent SoftwareVendors. By early 2005 the overwhelming majority of leadingISVs had produced versions of their products certified for use onRed Hat Enterprise Linux. Companies like Oracle, BEA,VERITAS, IBM, and SAP view Linux as strategically important totheir future success. Red Hat works closely with these vendorsto ensure that their products are fully integrated with Red HatEnterprise Linux, and to help them get to market faster. For acomprehensive catalog of certified applications for Red HatEnterprise Linux, visit: http://www.redhat.com/apps/isvcatalog.

If you require an application not listed, contact the vendor or RedHat to check on its availability. One of the major advantages ofselecting Red Hat over other Linux vendors is that we will workwith a vendor to get their applications to market if there is acustomer need.

Largescale Linux deployment

Large enterprises working with UNIX have often invested atremendous amount into developing a global deploymentstrategy. This may include an automated build and installsolution, a set of ISV management software components,system administrator training and skills development, anddocumentation of the entire process. Although there will certainlybe costs associated with adding Linux to such an environment,Red Hat has developed the knowledge and tools to make it aspainless and quick as possible. The primary goal in such ascenario is to provide a Linux deployment methodology thatallows enterprises to leverage existing infrastructure investmentsand inhouse administration and development skills. This beginswith the deployment technologies; UNIX systems are oftendeployed using the bootp protocol. Intel and AMD fully supportremote boot and install functionality with bootp and PXE. All thatis required is to make sure the Ethernet cards have the PXEcapable onboard eprom. Red Hat provides a tftp boot server thatcan be used to perform the installations. If organizations have awebpage or custom interface to configure the install process on


a persystem or subnet basis, there are tools available on Linuxfor that as well. For those using system imaging tools rather thanrelying on the actual native installation tools, it may be possibleto use the same tools for Red Hat Enterprise Linux, or there arealternatives available. Regardless of the specific technology, thegoal is to be able to invest in some development work upfront toconstruct a system that works just like the existing UNIX buildsystem to those installing the nodes. This allows the Linuxmigration to occur with minimal new investment in skillsdevelopment. Beyond the base OS there is generally a set ofISV applications used to manage the installed systems, as wellas a set of core applications needed to add functionality to theenvironment. As mentioned earlier, Red Hat has been working toensure such a software stack is fully available on Linux. To theextent that it is currently available, you are able to simply dropLinux systems into your existing infrastructure without changingany of the management components. Here is a quick look atsome of the management tools and operational applications thatare available:

Table 3: Deployment

Remote management capabilities

Once Linux is deployed, it is typical to support it from acentralized management location. The software components justoutlined are a part of that support. In addition, the standardrange of UNIX remote administration tools are available underLinux such as Telnet, FTP, SSH, scp, and rsh. Although theseservices will need to be selected within the bounds of yoursecurity policy, they are invaluable tools in managing deployedLinux systems and will likely continue to be integral to thesupport procedure in many enterprise situations.


Function Software Component

Asset tracking

System monitoring

Event monitoring RHN Monitoring Module, Trend SNMP

Backup

Job schedulingStorage connectivity VERITAS Foundation Suite

Software packaging RPM

Clustering

Tangram Asset Insight, Red Hat Network, Tivoli, Computer Associates UniCenter

RHN Monitoring Module, BMC Patrol, Tivoli, CA UniCenter, HP Openview

Amanda, Legato, VERITAS Net Backup, BRU, CA UniCenterCA Unicenter AutoSys Job Management, ControlM

Filesystems and Logical Volume Manager VERITAS FS (VxFS), VERITAS VM (VxVM), GFS

Red Hat Cluster Suite, Red Hat Global File System, Oracle 9iRAC, VERITAS Cluster Server, Legato, PowerPath v3.0.2 b069, GFS

Skills transfer and training

As a result of the close kinship UNIX and Red Hat EnterpriseLinux enjoy in terms of command line instructions, administrationtools, development tools, and the overall operating environment,the investment required to train existing development andadministration staff is usually fairly low. The skills migration forUNIX administrators and developers to Red Hat Enterprise Linuxis much simpler than a similar migration to Windows. Red Hat'scomprehensive skills development and certification curriculum(such as the RHCT, RHCE, and RHCA programs) provides ITmanagement with a complete program for skills transfer whenmigrating from UNIX to Red Hat Enterprise Linux. Additionalinformation on Red Hat's training and certification programs canbe found in the section of this paper entitled “Support Solutionsfor Linux in the Enterprise” and at www.redhat.com/training.

Directory and authentication services

Linux has been running in security and file serving capacities forquite some time and is very capable of integrating into the typesof infrastructures currently in use in UNIX productionenvironments. Kerberos, NIS/NIS+, PAM, NFS, openAFS,LDAP, Oracle Internet Directory, Open LDAP, SAMBA, andmany other authentication or directory related services are fullysupported.

Proprietary application porting and developmentThere are three primary types of applications Red Hat is typicallyengaged to help enterprise customers migrate to Linux: nativeC/C++ code, Java code, and scripts. The level of complexity ofdoing such a migration from UNIX to Linux is not very highrelative to a UNIX to Windows port. This section provides moredetail on the specifics of migrating applications to Linux.

A word about the GPL

One of the things that confuses enterprise clients most aboutmoving to Linux is the GNU General Public License, which hasbeen characterized by many as a viral license. This sinistermoniker simply means that there are certain conditions thatrequire that the license be extended to restrict the behavior ofthose developing code that utilizes the components of thelicensed software. Nearly all strict software licensing schemesare viral, including those used by Solaris and Windows. In thecase of the GNU General Public License, that condition existsonly when you link your code against code developed under theGPL. However, the C/C++ libraries and most of the otherlibraries and toolkits available on Linux are developed under theLGPL, or Lesser GPL. This license allows dynamic linking ofthese components, meaning proprietary development is perfectlyfeasible on Linux. A good example of an application that has


been built to run on Linux without needing to become opensource under the GPL is Oracle. Nearly all ISV applications areproof that the GPL and LGPL, though restrictive in rare cases,do not realistically prevent organizations from porting theirapplications to Linux and continuing to be the sole copyright andlicense holder of those applications. Red Hat has helpedhundreds of companies port closed source applications to RedHat Enterprise Linux through our services and is able to fullyinform customers of any GPLrelated issues as they arise.

The Linux development environment: C and C++

The development environment most UNIX developers havecome to expect is largely available under Linux as well. Let'slook at the C/C++ environment first, as that is where the majorityof porting work occurs. The fundamental framework for thisenvironment are the tools used to build C/C++ code: the Clibraries, compilers, build utilities, and debuggers. This is a quicklist of those tools as they exist for Linux:

Table 4: Development

There are a couple of detailed points that should be made aboutdevelopment for Linux. First, in general, Red Hat strives toachieve backward compatibility for all compiled programs. This isABI compatibility. Unfortunately, this is not always maintained asthe compilers and C libraries progress, so it is important tounderstand which versions of the compiler and C libraries areacceptable to use for specific targets. For each release of RedHat Enterprise Linux, the ABI will be stable as updates arereleased for the lifespan of the product.

Beyond support for the standard development tool chain, RedHat can provide Enterprise Tools Support for the GNUPro


Functions Software components Details

Build utilities Linker, make, Eclipse

Debuggers

C/C++ libraries C/C++ compiler

GCJ

glibc 2.2, glibc 2.3.2, glibc 2.3.3, gcc 2.96, gcc 3.2, gcc 3.4.2

Fully ANSIcompliant libraries and compilers. Red Hat Enterprise Linux 4 ships with glibc 2.3.3 and gcc 3.4.2 GCJ is a java compiler.

Linker is a category indexing program . Make is a compilation tool. Eclipse is an IDE tool platform

gdb, ddd

Gdb is the default debugger; several graphical or otherwise enhanced versions of gdb have been developed such as ddd.

compiler and tool chain. GNUPro is Red Hat's commercialversion of the gcc compiler and toolchain that can be customizedand maintained for your environment.

Technical features in the Red Hat Enterprise Linux developmentenvironment include:

• gcc 3.4 toolchain

• gcc "ssa" (4.0) toolchain included as a technology preview

• gcj / libgcj (Java gcc compiler frontend)

• gdb 5.3.90 including multithreaded core dump and gcore

• glibc 2.3.3 with RHEL 4

Thirdparty libraries

There are a number of open source thirdparty C/C++ librariesavailable for Linux for performing a range of operations fromsecurity to mathematical functions. Commercial libraries, such asmany of Rogue Wave's libraries, are available as well. This canbe fairly detailed information; please check with Red Hat formore information on specific needs. The libraries for graphicaldevelopment for GNOME and KDE are both included with RedHat Enterprise Linux. Although very few standard UNIXapplications have many graphical components, this can beappealing if you are migrating applications from Windows(although moving from the MSFC can be a bit time consuming).

Red Hat Developer Suite

Red Hat Developer Suite is a member of the Red HatApplications product family. Red Hat created the DeveloperSuite to simplify the migration of developer skills andapplications to Red Hat Enterprise Linux. It provides a fullyfeatured Integrated Development Environment (IDE) based onthe open source Eclipse project for application developers.Eclipse is an open extensible IDE that provides real valuebecause of the tool plugins. The tool plugins give the platformthe ability to work with many formats including Java files, Webcontent, graphics, video, etc. Eclipse additionally gives thedeveloper the ability to independently develop tools that can beeasily integrated with other tools or applications. For moreinformation on the Red Hat Developer Suite, please visit:http://www.redhat.com/software/rha/developer/.

Specialized porting tools

In some cases customers have wanted to develop specializedporting library sets for their environments to facilitate rapidmigration. Red Hat has tremendous compiler and libraryexperience and is able to help facilitate the development of suchtools. For more information, visit:www.redhat.com/support/offerings/developer.html.


Java and scripting languages

After C and C++ applications, the most common ports to RedHat Enterprise Linux are Java applications. This is a very simpleport, as Red Hat Enterprise Linux currently supports versions ofJava through 1.4. Also, middleware servers such as OracleApplication Server, BEA WebLogic, and development tools suchas Oracle Developer Suite and JDeveloper are fully supportedon Linux, meaning it is very easy to bring Java applicationsdeveloped for use on those platforms over just as quickly.Scripting languages, such as Perl, Bash, awk, sed, et al. arealso a fairly easy port; the real challenge is that the scriptsthemselves are usually referring to objects, files, or devices thatare named something slightly different in Linux. Global searchand replace is capable of resolving some of these, but oftenthese types of applications need a lot more attention for athorough port. In some cases, simply starting over is the bestidea.

Software packaging

Like some UNIX platforms, Linux supports the concept ofsoftware packages. In the case of Red Hat Enterprise Linux, thefacility that supports this is called the Red Hat PackageManager, or RPM. Much like Solaris packages, these are simplyCPIO archives wrapped up with some associated installationand deinstallation scripts. The development of RPM packagescan range from fairly simple to fairly complex depending on thenature of the application being installed. The infrastructure RedHat Enterprise Linux uses as an operating system is heavily builton RPMs, and much of our future support infrastructure will relyon RPM as a delivery and management component. As such,we strongly encourage clients to use RPM as the install methodfor their applications. As with Solaris packages, there are definiteongoing support and manageability benefits to doing so.

Supporting Linux in the enterpriseOne of the biggest concerns for IT managers considering RedHat Enterprise Linux for their enterprise is ensuringcomprehensive vendor support for globally deployed systems. Inthis context, vendor support encompasses the responsibility forthe functionality of the operating system as well as for migration,deployment, and ongoing usage. Red Hat's business model isbuilt around the delivery of endtoend services for all stages ofthe solution life cycle, from consulting (assessment,benchmarking, planning) through development and on tosystems and management.

Red Hat Global Support Services

Red Hat Global Support Services (GSS) provides telephone andWebbased technical support for Red Hat Enterprise Linux


customers. All GSS services are available as annualsubscriptions only. There are three levels of Production GSSservices available for the Red Hat Enterprise Linux product line.Basic subscriptions mostly address installation and hardwareconfiguration issues during standard business hours. Standardsubscriptions address everything associated with the basicsubscription in addition to typical service configuration issuesfrequently used in production environments during standardbusiness hours. Premium subscriptions are the highest level ofGSS services available and include 24x7 support.

Support for Red Hat Enterprise Linux is available for the baseoperating system and the services and packages outlined in thecorresponding Service Level Agreement for the subscription thecustomer purchases. Each annual subscription for Red HatEnterprise Linux products has a specific SLA. For moreinformation on Red Hat GSS Service Level Agreements pleasesee: http://www.redhat.com/support/service/sla.

Red Hat Enterprise Linux Annual Support subscriptions areintended to support individual systems and systemadministrators who are managing production systems. Red Hathas worldwide call centers open 24x7, staffed in seven nativelanguages to ensure Linux users are fully supported. This levelof support ranges from basic installation and usage questions tocomplex Level 2 configuration and usage issues. Level 3support, including bug fixes, workarounds, and security fixes, areincluded under these annual Service Level Agreements as well.

Global Support Services Technical Account Manager

Red Hat GSS Technical Account Managers (TAMs) provide aconsistent support interface between organizations whilebuilding a productive, proactive service partnership. The TAM isa highly skilled engineer assigned to provide technical accountmanagement and to assure your technical issues are dealt withquickly and effectively, ensuring the highest levels ofperformance on your Service Level Agreement. The TAM alsoacts as your champion within Red Hat Engineering, providingvisibility to the technical road map and ensuring that yourpriorities and requirements for Red Hat Enterprise Linux areconsidered during the release cycle. For more information, visit:http://www.redhat.com/support/offerings/technical.html.

Red Hat Global Professional Services

Red Hat Consulting Services provide consulting resources andexpertise to assist in Linux planning, development, ordeployment onsite. Services are intended for customersrequiring technical assistance beyond the Service LevelAgreements associated with GSS services. Services range fromreadiness assessment, infrastructure planning, andbenchmarking to system administration, development work, andinstallation and deployment assistance, all the way through staff


augmentation. Our consultants offer multi platform skills andexpertise, acknowledging that most enterprise IT environmentsare heterogeneous.

GNUPro enterprise tool support

Bundled with Red Hat's GNUPro Toolkit is Red Hat's annualcompiler and toolchain support for engineering developmentteams. This support ensures an ongoing link to the maintainersand drivers of the GNU software via updates on the latestversions of GNUPro Toolkit, access to the Red Hat Webbasedsupport portal, and patchlevel bug fixes.

Red Hat Global Learning Services

Red Hat offers training and skills development ranging fromintroductory courses to advanced system administration anddevelopment. The Red Hat Certified Engineer (RHCE) programis the most widely accepted Linux training standard and isavailable in training facilities worldwide. The Red Hat CertifiedTechnical Engineer (RHCT) is an ideal technicianlevelcredential for persons supporting Linux systems throughout anorganization. Meanwhile, Red Hat Certified Architect (RHCA)offers the highest level of certification in the industry today,providing proof of extensive, indepth system design andimplementation skills.

RHCT is a good choice for those transitioning to Linux from nonUNIX operating systems or who want to prove theircompetencies at a midway point on the way to RHCE, one of theten hottest certifications in the IT industry. Training can bedelivered in Red Hat training centers, onsite through our mobileclassroom, or for certain curriculum, through distance learningonline. Customized training courses can be developed aroundspecific requirements and delivered through any of thesemethods. For more information visit:http://www.redhat.com/training.

Red Hat Network

Red Hat is committed to reducing the overall cost to administerLinux systems in the enterprise. To do this Red Hat hasdeveloped several solutions that enable delivery andmanagement of Red Hat Enterprise Linux systems as part of anoverall service subscription. Rather than having to manage eachinstance and application on your Linux system, you can use asingle integrated Web interface to manage the complexity ofinstallation on hundreds or thousands of machines. The backend for this work can be hosted and managed entirely by RedHat, further reducing overhead.

Customers that wish to manage and maintain their own custompackages have the option of electing the onsite Proxy orSatellite Red Hat Network architectures. With the Proxy solution,


the customer's individual systems connect to a local RHN Proxythat sits behind the customer firewall. The Proxy aggregates allnecessary data in cache and communicates via a dedicated SSLconnection with the RHN servers at Red Hat. All informationstored in the RHN database is kept on the RHN servers. ISV andinternal customer applications can be packaged as RPMs andadministered to client systems via custom channels.

The Satellite architecture differs from the Proxy in that all RHNfunctionality is on the customer premise, allowing the customergreater functionality and customization. The Satellite server doesnot require a dedicated SSL connection to the RHN servers atRed Hat. Errata and updates are stored in an embedded Oracledatabase that is part of the Satellite model. The Satellite solutionallows customers to take their RHN solution completely offline ifdesired. The Satellite also offers customers more sophisticatedmanagement tools, channel permissions, errata cloning, theability to do PXE boot provisioning, and configuration filecustomization for specific systems sets.

In addition to the architectural variations of RHN, Red Hat offerscustomers a module choice. The Update module is included withall Red Hat Enterprise Linux subscriptions and includes updatesvia RHN for individual clients. The Management module allowsthe customer to group and manage many systems via a centralWeb interface. With the RHN Provisioning module, the system isable to replace kickstart image installation, rollback RPMs toreturn systems to their previous state, distribute configurationfiles to groups of systems, etc. In the future, RHN willincorporate much of the functionality of asset tracking software,event and monitoring software, and other remote administrationtools. This is an area of strategic investment for Red Hat, andthe services, with over 1.2 million registered client nodes, arealready proving invaluable to many of our largest customers.

For complete information on Red Hat Network offerings pleasesee http://www.redhat.com/software/rhn/.

Migration strategies

Suggested migration plans and timelines

Red Hat Enterprise Linux has proven to be an effectivereplacement for low to midrange UNIX/RISC systems. Clientsmay choose to develop a horizontal Linux support strategybefore deploying Linux or may take a vertical snapshot to provethat Linux can work in selected environments and gradually letthe infrastructure evolve. Something in the middle is typical, asorganizations need to prove that Linux is an effective solution fortheir environment before they can develop the entireinfrastructure to support it.

The following is a highlevel outline of a migration plan Red Hatdeployed for Fortune 100 customers, which we believe is a fairly


realistic path. This is intended to provide a cursory overview andsome general guidance for consideration. These project threadsmay be completed concurrently, reducing the overall time tomarket. Additionally, selected applications may be rolled outalmost immediately while work on the larger initiative continues.This allows the cost benefits to be realized now and not just atthe final deployment.

Phase 1: Pilot Project (3 Months)Key Goals:

• Determine status of required, thirdparty ISV applications

• Perform baseline OS benchmark comparisons forperformance and functionality

• Develop initial pass of a customized installation

• Begin documentation on an overall Linux deploymentmethodology

• Begin development of technologies central to the widespreaddeployment of Linux

• Port and test an initial internal application

• Begin determining which infrastructure components canquickly be switched over to Linux

• Begin determining which proprietary applications caneffectively be migrated to Linux

• Test Linux as a component of the existing UNIX infrastructure

• Gain general working skills with Linux

• Develop overall cost model for the move to Linux

Phase 2: Rollout Preparation (3 Months Key) Goals:

• Finish construction of deployment technology

• Build out infrastructure needed to deploy Linux worldwide

• Finalize the customized install of Linux, including ISVcomponents

• Produce enduser documentation

• Perform final deploy system QA

• Begin widespread application porting

• Begin rollout of infrastructure replacement components

• Begin training of system administrators or developers

Phase 3 Production (3 Month rampup, then ongoing)• Begin worldwide rollout


• Produce second cut of customized install with bug fixes

• Continue to port and develop new applications for Linux

ISV application supportBy late 2004 there were over 1000 ISV applications available forRed Hat Enterprise Linux. The Red Hat Solutions Catalog is alist of Red Hat Certified and Red Hat Ready applications that aresupported on Red Hat Enterprise Linux. Customers deployingthese applications have the assurance that the software hasbeen tested on Red Hat Enterprise Linux and is compliant withRed Hat's guidelines for interoperability. Red Hat Certifiedmeans that Red Hat and the application vendor have apartnership in place by which joint customers can be supported.Red Hat Certified Applications are reserved for Red Hat'sPremier Software Partners. Red Hat Ready applications havebeen tested by the application vendor on Red Hat EnterpriseLinux, and the vendor has agreed to comply with the Red HatReady Guidelines. Red Hat will use best efforts to supportcustomers using these products. This table gives a quick viewinto what ISV applications are certified on Red Hat EnterpriseLinux:

Table 5: ISV preview


Note: The information in the above table is subject to frequentchange. For complete and current of ISV application support forRed Hat Enterprise Linux, visit:https://www.redhat.com/apps/isv_catalog/ .

ConclusionRed Hat Enterprise Linux has made substantial leaps inscalability, functionality, and enterprise supportability in the lastseveral years. With the release of Red Hat Enterprise Linux v.4and the expansion of Red Hat's global technical servicescapabilities to help enterprises navigate the challenges ofmigration, Linux is wellpositioned as a compelling alternative toexpensive, proprietary RISC/UNIX solutions. Through ongoingcustomer feedback and increased enterprise deployment, Linuxcontinues to improve rapidly in processor scalability,


ISV Supported Applications

BEA

BMC

IBM

Oracle

Rogue Wave

Synopsis UFoundation 2003.03, 2003.06, 2003.09

BEA WebLogic 7.0SP1 and SP2, BEA WebLogic 6.1 SP4 and SP5, BEA WebLogic Platform 7.0, SP1, SP2, BEA WebLogic JRockit 7.0 J2SE 1.4.1, BEA Tuxedo 8.1, Various BEA WebLogic Adapters for WebLogic Integration

Patrol for MS – Perceive Web Server 7.1.01, Patrol for MS Perform 7.1.01, Patrol for MS – Predlct 7.1.01, Patrol for Unix 9.0.00, Patrol for UNIX Perceive Managed Nodes 7.1.01, Patrol for Unix – Perceive Web Server 7.1.01, Patrol for Unix Perform 7.1.01, Patrol for Unix – Predict 7.1.01

DB2 Universal Database Enterprise Server Edition 8.1, Informix Dynamic Server Enterprise Edition 9.4, Rational ClearCase 5.0, Tivoli Enterprise Console 3.8, Tivoli Storage Manager 5.2, WebSphere Application Server 5.0, WebSphere Application Server Enterprise 5.0, Numerous other IBM ApplicationsOracle10g Server Enterprise Edition, Oracle9i RAC, Oracle Bi Server, Oracle Express Server with 8.1.7, Oracle 9i Application Server Enterprise Edition with Bi or 9i Server, Oracle 11i eBusiness Suite, Oracle Collaboration Suite with Oracle Server Enterprise Edition 9i

Rogue Wave Application Tuning System, Rogue Wave Lightweight Enterprise Integration Framework, Rogue Wave XML Object Link, Source Pro C++ Core, Source Pro C++ Net, Source Pro C++ Analysis, Source Pro C++ DB

Sybase

Adaptive Server Enterprise (ASE) 12.5.0.3, Replication Server (RS) 12.5, Planned: Adaptive Server Enterprise (ASE)12.5.1 (32,64), Planned: Replication Server 12.6, Planned: Open Client/Server 12.5

performance, and functionality through the availability ofmissioncritical enterprise applications. Many Red Hat clientssimply want an alternative to proprietary UNIX, while someactively fear that specific flavors of UNIX are becomingmarginalized in the consolidation of UNIX so are looking for afuture migration path. Whatever the reasons for considering amigration, once Red Hat's have begun to use Linux, they havenot looked back.

If you would like more information about Red Hat, be sure tovisit: http://www.redhat.com, or call us at 1888REDHAT1.


Documents

Unix to Linux Migration - An Introduction