In with the New

Windows 2000, Novell NetWare, and Linux have all advanced in great leaps with respect to enabling more effective network storage architectures. In order to keep up with the ever-increasing data-storage demands of network users and applications, hard disk drive capacities have increased enormously, and new technologies for making that storage space available to users are constantly being developed. Here is a guide to the storage capabilities of these three operating systems, in their most recent forms, and an examination of the features that make them viable solutions for your network data storage needs.

Windows 2000 includes version 5.0 of NTFS, the NT File System, which increases the scalability of NT’s network storage subsystem and rectifies one of its most obvious omissions. Windows 2000 still supports the venerable FAT (File Allocation Table) file system, and adds support for the FAT32 file system first introduced in the OSR-2 release of Windows 95. But both of these functions are stopgaps intended to provide users with access to Windows 2000 drives when running other operating systems. NTFS provides the file and directory permissions needed to control access to the file system by network users, and provides support for the high-capacity storage subsystems often used on networks today.

This latest version of NTFS supports volumes up to two terabytes in size (although volumes up to 16 exabytes [16 x 2⁶⁴ bytes] can theoretically exist). The file system also provides the ability to encrypt individual files and directories for added security, and supports a sparse file attribute, which enables an application to create extremely large files without expending disk space on meaningless data. For example, a large database file may contain long strings of zeroes where previously existing data has been deleted. Rather than filling the disk drive with zeroes, a sparse file includes a reference to the amount of empty space that should appear at a particular location in the file. When the application reads the file, the system uses the reference to supply the data as it was originally stored.

NTFS 5.0 also includes disk quotas, a feature that has been available in Novell NetWare for years and sorely missed by converts to Windows NT. Disk quotas enable you to automatically monitor and restrict the amount of disk space utilized by particular users, so that they are unable to monopolize the network drives on which they store their files.

The NTFS 5.0 file system also maintains a log, called the USN (Update Sequence Number) Journal, of all file additions, modifications, and deletions on each volume.The USN Journal is itself a sparse file that contains timestamped records of all disk activities. This journal is one of the primary reasons why a Windows 2000 domain controller must use NTFS 5.0 on the partition it uses as its system volume.

New NTFS partitions created during a Windows 2000 installation use NTFS 5.0, and existing NTFS partitions are also converted to the new file system the first time they are mounted by Windows 2000. Windows NT can access NTFS 5.0 volumes, as long as Service Pack 4 or higher has been installed, but most of the new file system features, such as disk quotas, sparse files, and file encryption, do not function under NT.

NetWare’s file system has long been one of its strong points. Version 5.0 of the venerable network operating system includes a new feature called Novell Storage Services (NSS) that provides increased performance and support for virtually unlimited amounts of storage. NSS is a 64-bit file system that enables a NetWare server to host up to 255 volumes containing up to eight trillion files each. Individual files can be as large as eight terabytes and users can have up to one million files open at a time. These capabilities obviously far exceed those of the hardware available today; NSS is designed to support the storage technologies that will undoubtedly appear in the future.

NSS also improves the flexibility of the NetWare file system by being able to combine the free disk space on multiple storage devices into a pool from which NSS volumes are created, either manually or automatically. To increase your network storage capacity, you can install new devices and add their space to the pool. NSS can also mount CD-ROMs and FAT partitions as NSS volumes.

One of the problems with the traditional NetWare file system, which worsens as drives continue to grow in capacity, is the time required for volumes to mount. NSS can mount any size volume in less than a minute, using far less memory than standard NetWare volumes. NetWare servers can mount any NSS volume even if only one megabyte of RAM is available.

Because of its semi-commercial nature, the goal of the Linux operating system is not so much to be a competitor to commercial network operating systems like Windows 2000 and NetWare as it is to be an alternative. Emphasizing compatibility over innovation, Linux attempts to provide as many of the same capabilities of these other operating systems as possible. Various Linux releases include support for the SMB (Server Message Blocks) and NCP (NetWare Core Protocol) protocols used by Windows NT/2000 and NetWare (respectively) for network file sharing.

Virtually all Linux variants also include support for NFS (the Network File System) originally developed by Sun and currently implemented as NFS version 3. NFS is a client/server application that enables a server to export all or part of its file system. NFS clients mount the exported file systems and integrate them into their own local file system interface. NFS software is available for both Windows 2000 and NetWare, making it possible to build a network in which all three of these operating systems are able to access each other’s file systems.

Because Windows 2000, NetWare, and Linux have all been updated recently, their support for the latest data storage hardware available on the market is better than it’s been in some time. All three provide excellent network storage capabilities for the average network. Feature-wise, NTFS 5.0 leads the way with features like support for file system encryption and sparse files. NSS is preparing for on? future hardware developments by supporting storage capacities well beyond what is currently practical, but it does not yet include traditional NetWare file system features like data compression and block suballocation. Linux may not have a list of new and innovative features, but it still provides solid network storage capabilities at a rock-bottom price.

Craig Zacker is a freelance author, editor, and networker. His latest book is Updating and Troubleshooting Networks: The Complete Reference, published by Osborne/McGraw-Hill.