Upgrading and Repairing Servers

The sections that follow provide a more detailed discussion of each of the major server NOSs, with more explanation as to why each NOS is rated as it is. You'll also find references to resources for further reading.

Windows Servers

Microsoft Windows Server (www.microsoft.com/windowsserver2003/default.mspx) is probably the dominant application server platform on the market today, and it maintains a large minority of the servers in use today. On the desktop Microsoft reigns supreme, with perhaps 85% or 90% of the market share.

Three versions of Windows Server are currently deployed:

• Windows Server 2003 R2, which is the most current version and is an enhanced version of Service Pack 1

• Windows 2000 Server, which is currently at Service Pack 4

• Windows Server NT 4.0, which is currently being retired in phases but for which updates will still be available until 2007

The Windows NT kernel was based on the architecture of DEC VMS, which isolates devices using device drivers and organizes memory in a manner superior to previous Windows OSs. Windows 2000 Server incorporates Active Directory (AD). Just like NetWare 4, which incorporated Novell Directory Services (NDS)now called eDirectoryfrom its bindery days, Windows 2000 Server represented a major challenge to existing sites that needed to migrate their user and computer accounts from the NT 4.0 security system to the Windows Security Accounts Manager (SAM) subsystem security database of newer models (such as 2000 and 2003). Windows 2000 supported the concept of a mixed-mode domain where some of the systems could participate in Windows 2000's AD services, while others running older versions of the OS (both servers and clients) would only be able to participate in some of the AD features. When a complete Windows 2000only domain was established, the domain could be transformed to what is called "native mode," and the full complement of AD would be available for all network systems that were able to use it.

Windows Server 2003 added to Windows 2000 the graphical user interface (GUI) of Windows XP, enhanced the management tools and group policy features, and updated core components such as the IIS webserver service. Windows Server 2003 also enhanced AD and improved the components necessary to support the .NET web service initiative and framework. Microsoft publishes a major network management tool called the Microsoft Operations Manager (MOM), as well as System Management Server (SMS), currently up to version 2003. Some of the best network management tools available for Windows server systems are from third parties, including the following:

• LANDesk Management Suite

• Altiris Management Suites

• CA TNG Unicenter

• IBM Tivoli

• Argent

• Novell ZENworks

Microsoft considers the strength of its Windows Server platform to be that it's an integrated server environment. That is, Microsoft bundles many of the core servers and services into the OS's distribution. Thus, when you install Windows Server 2003, you automatically install AD if the server is the domain server (called the domain controller [DC]). You also install the IIS webserver for many application services, such as HTTP and FTP. You may also install and activate Windows Terminal Services so that clients can connect remotely to the server using the Microsoft Remote Desktop Protocol (RDP). All these services are installed through a single installation routine.

One of the primary differences between Windows and UNIX and Linux has been that the latter NOSs come with a much more fully developed command-line interface (CLI). While for the end user, a CLI is a clumsy, arcane interface that is difficult to make any use of, for an administrator it offers the ability to fine-tune a server much more quickly and efficiently than would be possible from a typical GUI.

Windows Server 2003 is available as several different editions:

• Standard Edition This offering supports up to four processors and comes with the management suite as well as the Internet webservers and terminal servers. It supports up to 4GB of RAM. The cost is $995, with five client access licenses (CALs). Additional CALs may be required for OS clients as well as application clients such as Exchange.

• Web Edition The Web Edition is a hosting and web application platform that sells for a little less than $400. You can use this version of the OS to develop websites and web services. It comes with IIS 6.0, ASP.NET technologies, and a 10-connection client limit.

• Enterprise Edition The Enterprise Edition of Windows Server 2003 supports up to 8 processors, supports eight node clusters with failover, and has 32GB of memory. There is a 64-bit version of this OS for Itanium systems.

• Datacenter Edition With support for up to 32 processors and 64GB of RAM in its 32-bit version, this OS is available for OEMs and VARs who qualify for Microsoft's certification program. The 64-bit version of this edition can scale up to 128-way SMP systems and 512GB of RAM, and it can be configured for up to eight node clusters. Included in this OS are load balancing and a system management utility called the Windows System Resource Manager.

Note

For a comparison chart of the features in the four different editions of Windows Server 2003, go to www.microsoft.com/windowsserver2003/evaluation/features/compareeditions.mspx.

Microsoft sells two versions of its OS that are really application servers, although it doesn't call them that:

• Microsoft Small Business Server 2003 (SBS) This product supports a single domain with no trust relationships, supports up to 75 connected users (provided that you purchase the CALs), and comes with a suite of applications, including Exchange, SharePoint, and a basic firewall. The premium version of this product adds both SQL Server and Internet Security and Acceleration (ISA) Server, which is a proxy, firewall, and caching server. SBS is aimed at the small office environment, and it isn't really suitable for a workgroup in a larger system because of the trust limitations.

• Windows Storage Server 2003 This is a highly tuned version of a file and print server. As with the Datacenter Edition of Windows Server 2003, you can't buy this version of the OS alone: You can only purchase it from a certified VAR or OEM as a hardware software bundle. The pricing for Windows Storage Server is aggressive, and this version doesn't require connected clients to obtain CALs.

Of the NOS vendors described in this chapter, Microsoft has the most complete line of application servers. The list of Microsoft servers that you can purchase as standalone applications that run on top of Windows Server 2003 or that Microsoft markets as part of a "solution" is extensive. Space precludes a full treatment of these servers here, but you can find a jump page at www.microsoft.com/technet/prodtechnol/servers.mspx and more information at www.microsoft.com/windowsserversystem/wss2003/default.mspx.

Among the most popular of Microsoft's server NOSs are Microsoft BizTalk Server, Microsoft Commerce Server, Microsoft Host Integration Server, Microsoft Identity Integration Server, Microsoft MapPoint Location Server, MOM, Microsoft Mobile Server, and Microsoft Windows Media Server, although the list goes on and continues to grow each year. Several of these servers are essentially unique offerings in the industry. Only Sun Solaris can compete with this list of application servers, but Sun's list would have to include many more third-party offerings to attain the breadth of application servers that Microsoft supports in-house.

The bottom line with Windows is that it is a safe play for many corporations due to Microsoft's excellent support setup. Other OSs, such as freeware versions of UNIX and Linux, have entry cost advantages over Windows, and although Microsoft argues that the support costs make Windows Server comparable, it's an argument that makes some assumptions. When you want to implement a unique Microsoft server or want more seamless integration with a set of Windows desktop clients, Windows Server has some pervasive advantages.

However, when the server you want to run is a standard (even an open source standard), other OS advantages come into play that can make the other NOSs better choices. For example, implementing any open source server application is more straightforward on Linux/UNIX/Solaris than it is on Windows, even though almost all versions of major open source applications have been ported to Windows. Furthermore, NetWare's sophisticated management applications argue for that NOS's consideration. Many consider Novell's eDirectory (formerly NDS) to be the state-of-the-art directory service, and that, along with superior security, makes NetWare very attractive. Also, NetWare has the widest compatibility with other OS in a heterogeneous environmentsomething that Novell stresses.

People argue about Windows Server's scalability and vulnerability, but there is really both less and more there than meets the eye. Windows scalability has been largely proven with the work Microsoft has done on Windows 2000 Server and Datacenter Edition. Microsoft now holds several significant performance benchmarks. However, the ability to buy a Sun Solaris server package is very attractive when it comes to scaling up systems and for mission-critical applications. Sun servers and Windows servers are considered to be the two standards that are supported by the storage industry for storage area network (SAN) applications. From a performance point of view, there isn't that much difference between these two platforms.

As to the security issue, it is undoubtedly true that Windows gets the lion's share of the efforts of hackers and sustains more exploits. The reasons for this are simple: There are many more users on Windows systems, Microsoft has tried to keep its systems open to encourage development on its platform. This has led to exploiters getting more bang for their buck in terms of the effort required to hack into the OS.

Novell NetWare 6.5

In the early 1980s, Novell NetWare was the name in PC networking. Although Novell lost much of its market share, and Novell as a company has had its ups and downs, Novell has redefined itself as a company. It has also positioned NetWare to be a very interesting and valuable server platform, directory system, and a wide variety of applications uniquely made to run on just about any NOS created, including Linux, which it also just acquired with the acquisition of Germany's SUSE Linux.

Novell's long history in the NOS and directory industry means that their file and print servers are solid and reliable and support a vast array of printing devices; their NDS is among the best platforms for heterogeneous client support; and their network management tools for servers are among the best in the industry. In well-established companies with long IT histories, you may be lucky enough to find a NetWare graybeard or two, but if you are new to networking and to servers, you should take a moment to consider some of Novell's offerings, particularly if you are in a heterogeneous environment.

NetWare was one of the last of the major enterprise networking platforms to accept TCP/IP as its native protocol, although Apple's Macintosh was also late in moving to TCP/IP as a native transport. (NWIP) was used. It was a modified and somewhat proprietary version of the IP Stack. With later NetWare version releases of version 5 and then 6, TCP/IP became the protocol for all core services, such as file and print services and directory services, and it was finally based on the industry standard. That version of the OS also introduced NDS. NetWare 5.0 predated Windows 2000 Server's introduction by about a year.

Note

You can find Novell NetWare's home page at www.novell.com/products/netware. At this site, the company offers a number of introductions and position papers describing its products.

Novell NetWare's current version is 6.5, and Novell advertises it as "the most reliable foundation for deploying business critical, open source-enabled solutions." Novell bundles the Novell Cluster Services solution into version 6.5, which allows you to create two node server clusters, both locally and as a failover to a remote location. Other new features that distinguish NetWare 6.5 are its native support for iSCSI, which is a server migration wizard and server consolidation utility, and the NOS built-in snapshot backup tool.

NetWare has offered a highly regarded directory service for well over a decade. NDS has been renamed and repositioned as a full-service, Internet-enabled directory called Novell eDirectory. NetWare 6.5 comes with a 250,000-user license for eDirectory, which supports AIX, HP-UX, Linux, NetWare, Solaris, and Windows.

With eDirectory you can store information about network users, employees, customer accounts, and so forth. NetWare 6.5 extends its file and print services with what Novell calls the Virtual Office. With Virtual Office, your users can set up an Internet print service (iPrint), a virtual online folder (iFolder), web file backup, web publishing, and email and password management.

NetWare also comes bundled with a browser-based network management tool that Novell calls iManager, which can inventory your network clients and servers. iManager includes tools for managing the DirXML tool that is used to exchange data with another directory service, such as AD.

The push to position NetWare as a very friendly, open source server has NetWare 6.5 bundling the following server software: the Apache webserver, the MySQL database, the Perl scripted programming language, and Jakarta Tomcat, which is the Apache Java-enabled webserver project. iManager can be used to manage these open source tools running on NetWare servers. NetWare also ships with the exteNd Application server (see www.novell.com/products/extend/), which is a Java 2 Enterprise Edition (J2EE) certified solution, and the Workbench application, which allows you to develop web applications on NetWare in the visual Integrated Development Environment (IDE) of exteNd Composer and exteNd Director. Java applications can then be ported to other NOS platforms based on the Java standard.

Novell has worked hard to position itself as the heterogeneous system and directory service provider of choice. In doing so, it has created a set of products aimed at supporting Windows and Linux/UNIX server/clients. Novell's desktop solution is Novell Linux Desktop (NLD) 9, which comes with the Novell Edition of OpenOffice.org, Novell Evolution which is an open source collaboration client, the Mozilla Firefox browser, and a multivendor instant messaging client for AOL, Yahoo!, and MSN. Novell's Linux solution is based on the SUSE Linux distribution, which is one of the better distributions for servers and corporate Linux.

Among the types of server products available for NetWare are the following:

• GroupWise This is the NetWare messaging platform.

• ZENworks ZENworks is one of the best heterogeneous network management platforms available today.

• eDirectory This directory service is lauded for large-scale Internet identity management but can be deployed on networks of all sizes.

• Desktop Management, Linux Management, Server Management, Handheld Management, and Asset Management (inventory) packages These packages represent capabilities that you purchase for other management suites, such as LANDesk or Altiris.

• Novell File System Factory This product extends the NetWare File System into a policy-based storage management system with provisioning capabilities. With this solution comes load balancing, logging and auditing, and integration of storage assets with the Nsure Identity Manager and LDAP directories.

• Nsure SecureLogin This is Novell's highly regarded single-signon or single-login tool.

The bottom line with NetWare is that it is a superior platform for network management, directory services, and file and print services. As an application server for open source applications, NetWare is better than Windows but no better than Solaris or a good enterprise version of Linux.

Sun Solaris

Sun Solaris, also called the Sun OS, is arguably the best-supported version of UNIX in the PC server marketplace. Many other vendors offer UNIX server platforms, but what makes Solaris special is that there are more applications running on Solaris than all the other UNIX versions combinedon the order of 10,000 or more. Sun has paid a lot of attention over the years to developers, particularly the ones developing network-based applications. That makes Solaris the only NOS that can compete with Microsoft Windows as an application server platform, with Windows being far and away the larger platform in terms of numbers of applications for desktop systems. This is a matter of opinion, of course; some think that IBM AIX may be the best-supported version of UNIX at the moment.

Solaris really got its boost from Sun's early adoption of the Internet as a strategic server platform, which predated Microsoft's Internet push by a year or two. At one point, webservers running Sun Solaris had a predominant share of the market, but this is no longer true today. Still, when you lump Solaris with other forms of UNIX and throw in Linux, it is still true that the large majority of servers on the Internet are UNIX- or Linux-based servers.

There's been a perception in the industry that UNIX in general and Solaris in particular is more stable, more secure, and better performing than Microsoft Windows Server. Sun has actively pursued performance benchmark records in the database and webserver arenas as proof of this superiority. With the introduction of Windows 2000 Server, Microsoft successfully bridged the performance gap between itself and UNIX and was also able to improve stability and security. However, UNIX is still the leading platform in terms of stability and security for all classes of servers, with the exception of mission-critical or data center servers.

Sun Solaris's biggest advantage is that it is sold into the marketplace as a hardware/software package. All the other enterprise server NOSs described in this chapter are sold as software packages only. When you buy from Sun's line of servers and run Solaris, you are running hardware that has been certified by Sun to be compatible with its NOS.

Note

Chances are that when you buy a Windows, NetWare, UNIX, or Linux server, you are buying that server as a package sold by a reseller, a value added reseller (VAR), or OEM. In those instances, you rely on your system vendor to certify that its hardware package is compatible with the OS it is selling.

Solaris comes in two versions: one that runs on the SPARC and UltraSPARC processors and one that runs on the Intel x86 processor platform. The vast majority of Solaris systems are deployed on Sun SPARC servers, and the bulk of the Intel x86 deployments are reserved for desktop systems and smaller servers. The exception to this rule is that Solaris 10 can be deployed on x86 64-bit systems, and there has been a considerable effort to market Solaris 10 x86 on entry servers running AMD 64-bit Opteron CPUs. Solaris 10 began to incorporate Linux APIs and can also natively run Linux binaries on the x86 platform.

The Sun OS is released under what is called the Common Development and Distribution License (CDDL), based on the Open Source Initiative (OSI) license model. Early versions of the Sun OS were based on BSD UNIX. When the code base moved to System V UNIX, the company adopted the name Solaris 2 and described major version releases as point releases. Thus version 2.8 is Solaris 8, 2.9 is version 9, and the current version of Solaris is 2.10, or 10. Common practice usually refers to Solaris by the point number only (for example, Solaris 10).

OSI is a nonprofit corporation dedicated to managing and promoting the Open Source definition for the good of the community, specifically through the OSI Certified Open Source Software certification mark and program. OSI tries to ensure that its certification mark and program allows you to be confident that software really is open source. OSI also makes copies of approved open source licenses and posts them at its site, www.opensource.org.

Note

For a jump page to a description of key features of Solaris 10 and a number of other learning resources, go to www.sun.com/software/solaris/ds/index.jsp.

There is no functional difference between installing Sun on a large server and on a desktop system. Pricing does change, of course, as do the services you activate on each platform. However, the installation is essentially the same. The Sun desktop environment started out using an OpenWindows GUI but switched to a Common Desktop Environment GUI in versions 6 through 9. Version 10 bases its Java Desktop System on the GNOME GUI, in an effort to make Solaris more friendly to Linux desktop users.

Sun's unique value proposition is that by combining a UNIX solution with hardware that Sun sells and supports, Sun has been able to develop solutions that scale and integrate particularly well. As Sun servers scale to larger numbers of processors, Sun has been able to get better performance out of more of its processors than other vendors have. In addition, a variety of leading-edge network services, such as IPv6, various streaming protocols, and 10Gbps Ethernet, appear on Solaris before they show up on other NOSs. However, Sun does make you pay a premium for its NOS on its equipment. The proficiency of Sun servers as network servers has an historical basis. Earlier generations of Sun servers were the routers of choice on the early Internet, and although that function has been replaced by specialized Cisco (and other vendors') routers. ISPs chose Sun servers because the Sun Solaris network stack was efficient, highly refined, and feature filled. The Sun/Solaris platform is still recognized for this networking strength.

Solaris 10 concentrated on adding a number of new networking features. Among the main new features added were an improved dual IP stack, better IPv6 support, Layer 3 multipathing (which offers better network redundancy), better streaming and session support, an improved Solaris Network Cache Accelerator (NCA), and a new technology called Solaris Containers (previously called N1 Grid Containers); these new features help implement a shared distributed processing model. Solaris comes with an NFS file server, an email server, and a DNS server (using BIND 8 or BIND 9 with IPv6).

IPv6 support also means that there is better support for the Solaris IPSec secure communications protocol and with the Internet Key Exchange (IKE) infrastructure. Sun likes to advertise Solaris as a "more secure" platform, which may be true in as far as Sun servers tend to be attacked or hacked less frequently than Windows servers are.

Note

For a list of Sun server applications, go to the jump page at www.sun.com/software/.

Sun's work on Java and in creating portable web applications means that Sun is one of the best web developer platforms on the market. Sun absorbed many of Netscape's server applications, giving the company a range of Internet servers that it has been able to build on. Thus Sun's directory servers, webservers, and applications servers are well-implemented and mature solutions.

Sun's product for integrating PC servers and clients into the Solaris network is Solaris PC NetLink. Using NetLink, you can have Sun servers play the role of Windows domain controllers, Windows file and print servers, and even Windows application servers. The implementation is for a Windows NT 4.0 server domain, which supports clients up to Windows XP, as well as both Windows NT 4.0 and Windows 2000 Server systems.

The integration of Linux into Sun's plans as both a desktop and server platform should help Sun better compete with other versions of Linux, whose growth in the market has largely taken place at the expense of Solaris. Linux users will find that they can now run the Java Desktop System and Java Enterprise System on Linux, as well as run Linux and Solaris on the same AMD Opteron and Intel X-86 systems.

Sun Solaris's unique value proposition is that it offers a stable, secure form of UNIX on supported hardware. Sun has an excellent network service suite and is a very strong network application and Internet platform (that is, a large number of third-party applications are available for the Solaris platform).

Solutions on Solaris tend to be more expensive than those on other platforms, and because you are buying proprietary hardware, there is a narrower choice of hardware from which to choose. Integration of network applications with desktop systems also tends to be not as smooth as it might be with Windows servers, simply because there are so many more Windows desktops deployed today. Sun and Microsoft are finally working together on interoperability issues, which means that Solaris's Windows support will probably improve over time. Sun lags behind Novell badly in this area of heterogeneous network management. It remains to be seen how well Sun will be able to entice Linux users to the Solaris platform over time, which is another important issue for this platform.

Linux

Linux is an interesting proposition as a server NOS platform because it has been embraced by almost all major server hardware vendors, including IBM, Hewlett-Packard, Novell, and others. The Linux OS is an open source project and is loosely based on UNIX, but it has its own kernel, which is what the name Linux actually refers to.

Most Linux commands are similar to their UNIX counterparts, but the internal architecture of the Linux kernel is unique. Anyone who distributes the Linux OS and conforms to the GNU GPL license is free to modify, sell, or give away his or her own version of Linux. GNU stands for "GNU's not Unix" and refers generally to software distributed under the GNU Public License (GPL). For more information about GNU, see www.gnu.org. Among the countries with major investments in Linux used in the enterprise are China and Brazil.

Linux runs on a variety of processor platforms, but it most often appears on the Intel X86 processor platform. The original version ran on the Intel 80386, but the Advanced Server version runs on 64-bit processors such as the AMD Opteron found in the Cray XD1 SMP systems. Linux's low cost has given the OS a position in small, embedded systems such as set-top boxes, PDAs such as the Symbian OS, phones, routers and firewalls from companies such as Linksys, and even the TiVo personal video recorder (PVR).

There are perhaps as many as 300 distributions of Linux (see http://lwn.net/Distributions/), ranging from packages such as Mandriva (formerly Mandrake) that are meant for desktop users to Novell's SUSE Linux Enterprise Server 9, which is sold as a server platform. The Red Hat Linux version of Linux dominates the sales of this platform for server applications.

The reason that Red Hat has been able to be as successful with their version in the past as it has been is that the company has arguably done the best job building a support organization to service its customers. Red Hat was one of the companies to go public during the Internet bubble, and it was able to leverage its IPO as well as investments for hardware partners to achieve this position. Red Hat also has one of the smoothest installation packages available for a Linux distribution, which is another factor in its success.

All that said, many companies have caught up to Red Hat in terms of Linux support; in particular, IBM and NetWare represent suitable, even better alternatives to Red Hat in many instances.

Other applications, such as Perl, a development language written by Larry Wall and widely adopted by the UNIX/Linux community, is sometimes replaced by PHP or Python, which are two additional widely deployed applications. PHP is a widely used general-purpose scripting language that is especially suited for web development (see www.php.net), and Python is a freeware open source, object-oriented, cross-platform, interactive, and interpreted scripting language (see www.python.org).

Although it's true that compared to the other OSs, Solaris and Windows have many more applications available to them, if you are installing an application server, you are probably doing it for one or two purposes at most. In addition to the open source programs mentioned earlier, Red Hat Enterprise Linux Server version 4 (RHEL 4; see www.redhat.com/software/rhel/) will run Oracle databases, IBM DB2, many VERITAS applications (but in particular the VERITAS backup suite), and BEA's management software. This is just a partial list of what's available, so you should check Red Hat's website (www.redhat.com) for more details.

Red Hat used to sell both a desktop and a server version of Linux but dropped out of the desktop market for a while after version 9 to concentrate on its server product. The desktop version of Red Hat is now developed and distributed as part of the Fedora project. However, Red Hat now offers what it calls Red Hat Enterprise Linux WS (for workstation) and Red Hat Desktop in 10 and 50 packs or bundled with Red Hat Network Proxy and Satellite Server. The WS client version is aimed at users creating software and those with high-performance computing needs such as graphics or CAD.

RHEL 4 comes with the Linux 2.6.9 kernel, which has improved the speed of the product over previous versions. Red Hat markets RHEL 4 in two versions: a base server NOS and an Advanced Server version. RHEL 4 AS is the version that is meant to run on large SMP and 64-bit processor systems.

One of the main improvements in RHEL 4 was the introduction of the Security Enhanced Linux (SELinux) kernel modification. When you install RHEL 4, SELinux is automatically compiled into the OS so that it is always included by default. One thing you may notice if you work with this OS is that it eliminates the vulnerabilities associated with the superuser or root user and the way in which other passwords and privileges are managed. The kernel is designed to directly manage server applications and allows the administrator to control and manage even privileged services. This prevents a user from gaining root user status and running a process that can exploit an entire server. RHEL 4 may have some issues with older applications, but there are workarounds to these issues that involve modifying some of the SELinux parameters.

One thing you may also notice is that SELinux allows you to set policies, although in its first version, reviewers have reported that policy management on RHEL 4 isn't anywhere near as smooth as it is in NetWare 6 or even AD's Group Policy management scheme. Consider this a work in progress.

One of the major criticisms of Linux is that it can be difficult to obtain stable Linux device drivers. Support for many items that servers rely on normally depends on the work of the open source community. However, because Red Hat has been able to achieve a central market position, most of the vendors who intend for their equipment to run on Linux serversRAID controllers, iSCSI adapters, Gigabit NICs, and so onall certify their products against Red Hat Linux. It's considered to be the de facto standard in the industry for enterprise Linux. Red Hat has put a lot of effort into making its Anaconda installer's hardware detection routines as robust as those of any of the other major NOS platforms, and version 4 not only dramatically added to the number of devices recognized but also resolved issues with some of the more troublesome devices, such as embedded motherboard controllers and a wider range of NICs.

RHEL 4 uses the ext3 file system, but RHEL 4 also offers the Global File System for clustered 64-bit large-scale deployments. RHEL 4 added support for Sun NFS version 4, adopted Samba 3 file and print services for Windows clients, and added upgraded versions of most of the bundled enterprise server applications that shipped previously with the product.

Red Hat has begun to delve heavily into the application server market, selling solution-type products. It advertises a modular web-based Linux management and infrastructure platform called the Red Hat Network (RHN) that has access to RHN Update Module and the Management and Provisioning module. You can deploy this internally or use all or part of it as a hosted solution. Among the application servers that Red Hat sells are Red Hat Application Server, a J2EE 1.4 application server that features Tomcat and EJB Container and is based on JOnAS. You can deploy the Global File System as a server for databases and grid applications, and you can use GFS for support of the Red Hat Cluster Suite. Some large and powerful cluster applications have been built using Red Hat Linux servers and high-speed interconnect technologies. Finally, Red Hat also offers a developer's suite as a server, and the Red Hat IDE is based on the Eclipse tools.

Most organizations adopt Linux servers for two main reasons: the lower cost of licensing the OS and the modest equipment demands of Linux. Although RHEL 4 makes strides at bridging the gap between Linux as a management platform by improving AD interoperability and adding policy management, most organizations choose Red Hat Linux servers as a platform for running open source server applications, such as Apache. As an application server platform RHEL 4 is better than Novell's NetWare for open source applications, but it is not nearly as strong as either Sun Solaris or Microsoft Windows Server for the depth and breadth of the server applications available.

If you are considering RHEL, you should be aware that Novell has an enterprise Linux platform in the market and that Sun will be releasing a Linux-based server product in the near future. In 2006 and beyond there will be more and stronger competitors in this market for Red Hat to compete with.