ONE GREAT STRENGTH OF WINDOWS NT is its ability to support multiple file
systems. This ability stems from NT's modular approach to file system support.
To support each file system, NT uses a low-level driver that's part of the
Windows NT Executive. So creating support for additional file systems is as easy
as developing and installing a new driver. (The sidebar, "Windows NT File Systems," on page 96, shows the file systems available under NT and
provides a general description of each.)
An important decision in setting up an NT system is choosing a primary file
system. With NT 3.5x, you had a choice of three file systems: NT File System
(NTFS), File Allocation Table (FAT), and the OS/2 High-Performance File System
(HPFS). In addition to support for the NTFS and FAT file systems, NT supports
the CD-ROM File System (CDFS) for accessing data on PC-compatible CD-ROMs. NT
4.0 supports NTFS and FAT (to see how to make HPFS work with NT 4.0, see the
sidebar, "Using HPFS with NT 4.0," page 98).
To decide what's right for your situation, you need to understand NTFS's and
FAT's capabilities, advantages, and disadvantages. The sidebar, "Choosing
an NT File System,"
on page 100, presents the pluses and minuses of both
file systems. Let's start this look at file systems by clarifying some
disk-related concepts and terms.
Disky Business
Every disk can contain partitions, or structural divisions. The two
types of drive partitions are primary and extended. A
primary partition is the only type that can contain an OS. You can
assign a drive letter to each of up to four primary partitions on one physical
drive. An extended partition is a special type of partition that you can
subdivide into one or more logical drives. Each logical drive can have
its own drive letter. You can have only one extended partition per physical
drive, but the extended partition can have multiple logical drives (the number
of logical drives on an extended partition has no practical limit). Each primary
partition and each logical drive is formatted independently and can use a
different file system.
A volume is a primary partition or logical drive that you format
with a file system. In fact, any medium you can format, including a removable
disk such as a floppy or CD-ROM, can be a volume.
System and Boot Partitions
NT gives special names to particular disk partitions. For example, the system
partition contains hardware-specific files for booting the system. These
files include the NT Boot Manager and boot.ini, ntdetect.com, and ntldr (osloader
on RISC-based systems). The system partition can contain the NT installation
directory.
On Intel x86-based computers, you can format the system partition with FAT
or NTFS. On RISC-based computers, you must format the system partition with FAT.
FAT partitions don't have NTFS's security capabilities, so NT 4.0 includes a new
feature to secure the FAT system partition on a RISC-based NT system. From the
NT Disk Administrator's partition menu, choose Secure System Partition.
The system asks you to confirm the request. Click OK, and reboot the system to
activate security on the system partition. With this feature, only
Administrators group members can access the FAT system partition.
Another NT disk partition is the boot partition. Despite its name,
this partition isn't necessarily the drive the system boots from. Instead, it
contains the NT installation directory you choose during NT setup. The term boot
refers to the files required to start NT, not the computer. The boot partition
can be the same as the system partition. On RISC and Intel NT systems, the boot
partition can be on a FAT or NTFS partition.
For maximum system security, administrators of RISC-based systems will want
to consider separate partitions for the boot partition and the system partition
and consider securing the system partition with the Secure System Partition
option. This approach puts the NT system files on an NTFS partition (for better
security and protection from data corruption than with FAT) and prevents access
to the NT system files if the system boots from a DOS floppy, unless you use
NTFSDOS (a shareware utility that can access an NTFS drive)--for information on
NTFSDOS, see Mark Russinovich and Bryce Cogswell, "NTFSDOS Poses Little
Security Risk," and Joel Sloss, "That Depends on Your Definition of
Secure," September 1996).
The FAT File System
FAT is the granddaddy of all PC file systems. Several flavors of FAT have
emerged over time, but the core technology is largely unchanged.
Features
Experienced DOS users will recognize some distinguishing characteristics of
the FAT file system. It uses the file allocation table (FAT's namesake) to track
files and directories. The system stores this table near the beginning of the
FAT volume. To prevent corruption, the system automatically maintains a second
copy of the table on the disk and can access this copy if the primary table
becomes corrupt. The table and the volume's root (main) directory must be in
specific locations on the disk so the system can access files needed to boot
from a FAT volume.
The table needs constant updating, which requires that the hard drive heads
continually return to the beginning of the volume. As a result, FAT can
cause a severe performance hit on large volumesthe larger the volume, the
greater the performance penalty.
FAT stores files on a first-come, first-served basis: The system writes
files to disk in the first available area. Over time, this method can result in
heavy file fragmentation (files are in multiple, noncontiguous disk blocks) on
FAT volumes and is another performance killer. To remedy this problem, you have
to run a disk defragmentation program.
As of this writing, the only NT disk defragmentation tool is Executive
Software's DISKEEPER for Windows NT. No one utility can work with all the NT
versions and service packs, and DISKEEPER is no different. With NT 3.5x,
fragmentation utilities had to be specific to a particular NT version or service
pack. If you use such a utility on a different version or service pack level,
you can corrupt data. NT 4.0 solves this problem by including a disk
defragmentation API. You can expect to see several new NT defragmentation tools
available in the near future.
Another disadvantage to FAT is that its directory structure has no formal
organization, so FAT can't automatically sort folders and filenames in a
directory. Locating a file on a large FAT volume can take longer than searching
an NTFS volume with automatic directory sorting.