File Systems

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Windows 2000 network file sharing is based on the traditional Microsoft networking mechanism of server message blocks (SMBs). UNIX systems, on the other hand, use the Network File System (NFS)—originally developed by Sun Microsystems—to share file systems across the network.

Until the release of SFU, only third-party NFS solutions were available for Windows systems that needed to be able to share file resources with UNIX systems. Most of these third-party solutions were expensive and problematic. The biggest issue was their inability to keep up with Windows NT service packs, which seemed to break these NFS solutions more often than not. In addition, these solutions often had significant performance problems.

However, several powerful SMB-based UNIX solutions address the problem of sharing file resources between Windows NT and UNIX. These SMB solutions vary in cost from free to expensive and support native Windows networking at either the workgroup or domain level. With the release of Windows 2000, only time will tell how well these solutions will manage to keep up with the changes in the Windows 2000 security model as compared to the Windows NT model.

The Network File System

When it was created, NFS was designed to run as a broadcast protocol using User Datagram Protocol (UDP). This protocol created substantial performance and network traffic issues for those intending to implement large amounts of NFS networking and made it difficult to share file systems across routed boundaries. Eventually, the NFS standard was changed to support TCP for NFS networking, and many modern clients and servers support this mechanism. However, many older NFS implementations still out there don't support TCP, so the default mechanism for SFU and other NFS implementations in Windows 2000 is UDP.

Overall, performance of NFS file transfers to and from a Windows 2000 Server is substantially inferior compared to most SMB implementations. For environments in which large files must be routinely copied back and forth between Windows 2000 and UNIX systems, NFS is likely to be an unsatisfactory solution. However, if your needs are more for transparent access to UNIX resources residing on UNIX servers, NFS is the way to go. It provides a fully integrated environment to the Windows 2000 user. (If you install SFU as it's presented later in this chapter, keep these considerations in mind.)

The Server Message Block

The biggest issue that the SMB-on-UNIX crowd has to deal with is the changing Windows 2000 security model. Two mechanisms are used for handling security with the SMB-on-UNIX solutions—workgroup-level security and Windows NT 4 domain-level security.

Workgroup security suffers all the same problems as workgroups in the enterprise environment: it becomes more difficult to manage as the number of users and machines involved increases, and it has limited options for actually managing security. However, workgroup security has a definite place in the smaller environment, where it's easy to understand and simple to set up. Plus, there's a nice cost advantage—a widely available and well-implemented freeware SMB server called Samba is available on virtually all UNIX platforms. Other commercial workgroup SMB servers are also available that run on a variety of platforms. They tend to be more Windows-like and easier to setup and administer than Samba, which shows its open source heritage.

Windows NT 4 domain SMB servers are also available from a number of UNIX vendors. All of these are based on AT&T's initial port to UNIX of Microsoft's advanced server technology. Each is limited to running on the platform for which it was designed, and each has slight differences because the port from AT&T required tweaking in most cases. All SMB servers can be either a primary domain controller or a back-up domain controller in a Windows NT domain, but all will have problems dealing with the new security model in Windows 2000. These servers, being based on the Windows NT 4 security model, will force you to stay in mixed mode, unfortunately.

The SMB domain servers do have one important advantage over the SMB workgroup servers: to the users and administrators of the Windows network, they all look and feel exactly like a native Windows NT 4 server. The familiar Windows NT Server administration tools are used to manage them, and servers and shares look exactly like a Windows NT server to your users, eliminating training and user-interface issues. Also, all of the SMB servers have one advantage over the NFS solutions: they tend to be significantly faster at file transfers, especially when handling large files.