Upgrading and Repairing Servers

All major NOSs share certain features in common. Common features found in all of the NOSs include the following:

• Computer and user identification services

• Logon services

• File and print services

• Standard network transport support, mainly TCP/IP version 4

• Network addressing and name resolution services, primarily DHCP and DNS

• Web services, in the form of Hypertext Transfer Protocol (HTTP) and browser support

• Messaging, in the form of POP3 and IMAP

• Heterogeneous client support

All the OSs that are described in this chapter have most, if not all, of these features. In addition, each of the features listed here are based on industry standards (which makes them less proprietary) and are fully implemented into each respective NOS. As an example, TCP/IP (the protocol most widely used on the Internet and beyond) is based on widely accepted industry standards and is implemented into every NOS or OS released today. Before TCP/IP was so widely used, software and hardware vendors used proprietary solutions such as IBM's System Network Architecture (SNA) protocol, Apple Macintosh used the AppleTalk protocol, and Novell NetWare used the Internet Packet Exchange/Sequenced Packet Exchange (IPX/SPX) protocol. And that's just to name a few. All three of these proprietary protocols worked like TCP/IP, but they needed to be translated for each other, which caused significant configuration and management issues. Therefore, standardizing on using one protocolTCP/IPbetween all systems made sense. For example, each of the NOS supports DNS. They have to, because if they didn't their DNS wouldn't work properly with the service on the Internet. In the past, when you purchased a NOS such as Novell NetWare or Apple Macintosh, you were buying into using IPX/SPX or AppleTalk as a native protocol. While there is still support for these protocols to support legacy clients, today the native transport for all NOSs is TCP/IP.

So if all these NOSs are so similar, what exactly are the differences that would help you decide to choose one over another? Differentiation between NOSs is a function of the following:

• Pricing and delivery models

• Third-party developer support, as evidenced by available server applications (what we refer to in this chapter as an application server or overall as an application platform)

• Integration with heterogeneous clients

• Directory services

• Policies

• Management tools and style

Table 18.1 lists some of the characteristics of the different server NOSs so that you can compare them quickly; Table 18.2 is a general rating of the major NOSs described in this chapter, by features.

With all this information in hand it begs the question: Does the type of NOS you use matter? The short answer to this question is both yes and no. Because all NOSs offer the same basic functions, and those functions are based on industry standards, each NOS has enough tools to let you run a successful network. No matter which NOS you choose to implement, you will be able to create most standard services. There's less difference between all the NOSs than their respective vendors would care to admit.

If you are choosing a server platform to run only one significant network service or application, your decision may hinge on whether the application you want to run exists on the platform of your choice or on whether you want to use a different application that runs only on a different platform. Consider a situation in which you want to create a website, and you are considering which platform to use for this. After comparing different webservers, you may decide to implement Apache. This isn't an endorsement of Apache as the best-of-breed webserver, but you think that Apache has a number of advantages going for it. One of Apache's advantages is that there are versions of Apache that run on nearly all NOSs. Chances are that you wouldn't implement Apache on Windows Server 2003 (or 2000) because Microsoft's Internet Information Server (IIS) has a number of special advantages on that platform that cater to the underlying NOS. However, you'd be equally well served (for different reasons) running Apache on Linux, Solaris, or some other NOS server platform.

The NOS definitely does matter when it comes to some specialized application or service that just isn't available on another platform. That would be the case for an application such as Novell's eDirectory, or Microsoft's Commerce Server. Selection of either of those products would in effect limit your choice to those two NOSs. If you decided that you wanted to install an ERP (enterprise resource planning) package like SAP's solution, you would be opting for either a UNIX or Windows server because that is what the vendor supports. A choice between those two platforms for SAP would boil down to which of the two platforms made the most sense in terms of integration into your established infrastructure.

NOS vendors do their best to lock you into a single solution, their servers, and their desktops. Their rationale is that by investing in a single solution, you minimize your support costs and eliminate a lot of complexity. There's merit in that argument. However, if you are building an industry-standard server, such as a file server built on the open source package Samba 3, then once the server is set up, it is probably going to be left as is for some time to come. There's some initial setup penalty but little extra grief once you are past those problems, generally speaking.