PC Hardware in a Nutshell, 3rd Edition [Electronic resources] نسخه متنی

14.6 Preparing a Hard Disk for Use

After you have physically installed the
hard disk and configured CMOS Setup to recognize it, that drive must
still be prepared before it can store data. This process requires
three steps:

Low-level formatting, also called
physical formatting, records the tracks and
sectors that are used to store data. Low-level formatting occurs at
the hardware level, and is independent of the way that the disk will
be divided and of the operating system that will use it. All ATA and
most SCSI drives are low-level formatted at the factory, so you may
not need to perform this step yourself.

Partitioning divides the physical disk into one
or more logical sections, each of which will contain one or more
logical volumes identified by drive letter or a mount point under
Linux. Any hard disk must contain at least one partition with at
least one volume. Any new hard drive must be partitioned before it
can be used.

Logical formatting, also called
high-level formatting or DOS
formatting, creates within the volume the logical disk
structure (called the filesystem) needed by a
particular operating system to store its data. Drives that will be
accessed by DOS, Windows 3.X, and Windows 9X use the FAT filesystem
(which comes in several variants). Windows NT/2000/XP uses either FAT
or NTFS filesystems. Linux generally uses ext2, but ext3 is becoming
more common.

The following sections examine each of these steps in turn.

14.6.1 Low-Level Formatting

Low-level formatting a hard drive
lays down the tracks and sectors that will be used to store data and
also embeds servo information that the drive head positioning
mechanism uses to locate those tracks and sectors. Modern drives are
low-level formatted at the factory, and cannot be low-level formatted
by the user.

You sometimes need to low-level format a drive, or at least do
something that resembles a low-level format. The three most common
situations that require formatting a drive down to bare metal are the
presence of a virus that cannot be eradicated by a logical format or
by repartitioning the drive, a corrupted partition table that cannot
be corrected by using a partitioning utility, and a drive that is
beginning to develop bad sectors.

For all these situations, the solution is to pseudo-low-level format
the drive with the maintenance utility provided by the drive
manufacturer. Although these utilities do not do a true low-level
format, they write binary zeros to every accessible bit on the drive,
wiping all data and partitions from the drive. These utilities also
typically have a sector-sparing function that allows them to detect
bad sectors and swap them out for a spare sector, returning that
drive to its factory-fresh, error-free state.

If you need to do a low-level format of your drive, download the
latest version of the low-level format utility from the
manufacturer's web site. Create a DOS-bootable
diskette, and copy the low-level format program executable to that
floppy. Boot the floppy and run the format program, carefully
following all instructions supplied with the utility.

Most SCSI host adapters include a low-level format utility in ROM.

14.6.2 Partitioning

The
next step required to prepare a disk for use is called
partitioning. Partitioning logically divides a
disk into segments, each of which can be logically formatted to store
data in the format, or filesystem, used by a
particular operating system.

14.6.2.1 Understanding partitioning

Each physical disk must have at least one partition, and may have as
many as four. Creating the first partition on a physical disk drive
creates the Master Boot Record
(MBR) for that disk and writes the MBR to the
first physical sector. Subsequent changes to the partitioning of that
disk, no matter which operating system makes them, update that single
MBR. The MBR on each physical disk contains a section called the
partition table. The partition table tells the
computer and the operating system how the hard disk is logically
divided and how to access the information stored on that hard disk.

There are two types of partitions. A primary
partition is one from which the computer may be booted.
Each primary partition is logically formatted as a single volume for
a particular operating system and is assigned one drive letter. A
primary partition may occupy all or part of a physical hard drive,
and a single hard drive may contain from zero to four primary
partitions.

The second type of partition is called an extended
partition. An extended partition is essentially a virtual
physical disk, which may itself be subdivided into logical volumes. A
disk may contain zero or one extended partition. The computer cannot
be initialized from an extended partition, although the operating
system files may reside on a volume located on an extended partition.

Extended partitions are neither formatted nor assigned drive letters.
Instead, extended partitions are further divided, or subpartitioned,
into logical volumes, each of which may be logically formatted and
assigned its own drive letter under Windows or mount point under
Linux. Each of these logical drives may be treated as an independent
entity. You might, for example, create an extended partition,
subdivide it into two logical drives, and then format one of these
drives for FAT and the other for NTFS.

If a physical disk contains multiple primary partitions, you may
format each primary partition for a different operating system, and
mark one primary partition as active, which
causes the computer to boot the operating system contained within
that partition. Using multiple primary partitions is one way to
install and boot multiple operating systems from the same hard disk.
For the system to boot from the hard disk, at least one partition
must be marked active. To change which operating system boots, you
must use fdisk or another partitioning utility
to change the active partition.

Windows NT/2000/XP refers to the active partition as the
system partition. It contains the
hardware-specific operating system bootstrap files needed to
initialize the computer and begin the boot process. A disk may also
contain a boot partition, which may be located
on either a primary partition or a logical volume within an extended
partition. The boot partition contains the remainder of the operating
system files needed to load and run the operating system. The system
partition and the boot partition may be (and often are) the same
partition, or they may be located in different partitions, including
those located on separate physical disk drives.

The system partition must be located on a primary partition, but the
boot files of another operating system may share that primary
partition. For example, one convenient way to dual-boot Windows 98
and Windows NT is to partition the disk with an active primary C:
partition and a D: volume, which may be a primary partition or a
logical drive in an extended partition. Installing Windows 98 to C:
makes that volume bootable. Installing Windows NT to D: automatically
installs the boot files to C:, making it the NT system partition, and
installs the remainder of Windows NT to D:, making it the NT boot
partition. Windows NT Setup also installs a boot manager, which
allows you to choose between booting Windows 98 and Windows NT when
you start the system. The advantage to implementing dual-boot this
way is that you don't have to change the active
partition to boot the other operating system.

To summarize:

To be accessible to the operating system, each physical disk drive
must contain at least one and at most four partitions. These
partitions may be primary partitions or extended partitions.

A physical disk drive may contain from zero to four primary
partitions, each of which is formatted as a single unit and assigned
its own drive letter. Each primary partition is formatted for a
single type of filesystem. Different primary partitions on the same
physical disk drive may be formatted for different operating systems.
A primary partition may be any combination of (a) a system partition,
which is used to start the operating system, (b) a boot partition,
which contains operating system files, or (c) a general-purpose
partition, which is used to store user files.

A physical disk drive may contain zero or one extended partition. If
the drive contains an extended partition, it may contain at most
three primary partitions. An extended partition may be divided into
one or more logical volumes, each of which may be formatted to
contain a single type of filesystem. Different logical volumes within
an extended partition may contain different filesystems.

The system partition, also called the active partition, is a primary
partition that contains the hardware-specific files needed to
initialize the system and begin the boot process. Exactly one active
partition must be present on the computer for it to boot.

The boot partition contains the remaining files needed to run the
operating system. The boot partition may be located on a primary
partition, or on a logical volume within an extended partition. The
boot partition may be and often is the same partition as the system
partition.

14.6.2.2 How drive letters are assigned

Partitioning a disk with DOS or
Windows assigns a drive letter to each primary partition and each
logical volume created in an extended partition, a process called
dynamic drive letter assignment. Adding and
partitioning another hard disk or changing partitions on an existing
hard disk may cause existing drive letters to change, which can
confuse programs that expect themselves or their data to be on a
particular volume and suddenly find that is no longer true. Modifying
partitions under DOS or Windows 9X assigns drive letters as follows:

Physical disks are numbered sequentially. The Primary Master is Disk
0, the Primary Slave is Disk 1, the Secondary Master is Disk 2, and
the Secondary Slave is Disk 3. For SCSI disks, the drive with the
lowest SCSI ID is Disk 0, the one with the next-higher SCSI ID is
Disk 1, and so on.

The first primary partition on each physical disk, beginning with
Disk 0, is assigned a drive letter sequentially, beginning with C:.
The first primary partition on each higher-numbered disk is then
assigned the next drive letter in sequence. A disk that has no
primary partition is skipped during this process.

Starting with Disk 0, each logical volume is assigned a drive letter.
All logical volumes on each disk are assigned drive letters before
drive letters are assigned to any logical volumes on higher-numbered
disks.

Once all logical volumes on all disks have been assigned drive
letters, the remaining primary partitions on each disk with
unassigned partitions are each assigned a drive letter.

Assume, for example, that a computer has one physical disk,
partitioned into one primary partition labeled C: and an extended
partition that contains two logical volumes labeled D: and E:. If you
then add a second disk and create on it a primary partition and an
extended partition that contains two logical volumes, drive letters
are reassigned as follows: the primary partition on Disk 0 remains
C:; the primary partition on Disk 1 becomes D:; the two logical
volumes on Disk 0, formerly D: and E:, are reassigned as E: and F:
respectively; and the two new logical volumes on Disk 1 are assigned
G: and H:.

To avoid this reassignment of drive letters, do not create a primary
partition on the new hard disk. Instead, partition the entire disk as
an extended partition and create three logical volumes within that
partition. This leaves the original C:, D:, and E: drive letter
assignments unchanged, and assigns F:, G:, and H: to the three new
logical volumes. The only drawback to partitioning a disk without a
primary partition is that the disk can never be made bootable without
being repartitioned to contain a primary partition and then
reformatted.

Windows 2000/XP partitioning works differently because it uses both
dynamic drive letter assignment and static drive letter
assignment. Before you run Windows 2000/XP Disk Management
(Computer ManagementStorageDisk
Management) the first time, Windows uses dynamic drive letter
assignment to assign drive letters as described earlier. Running Disk
Management converts these dynamic drive letter assignments to static
drive letter assignments, which means that adding a new disk no
longer causes drive letters to be updated automatically. You can,
however, use Disk Management to reassign static drive letters
manually to volumes. To do so, display a list of volumes within Disk
Management, display the context-sensitive menu by right-clicking the
volume label for the volume you want to change, and choose the Change
Drive Letter and Path option. You can assign any drive letter that is
not already being used by a local or network drive to any partition.
Don't change the drive letter assignment for the
system partition, though, because many applications and services
assume that the system partition is C:.

14.6.2.3 Partitioning a hard disk

With only minor exceptions, partition tables and partitions are
completely standard. This means, for example, that DOS can access a
partition created by Windows NT and vice versa. You
don't have to partition a disk using the native
utility of the operating system that you plan to install on that
partition. In broad terms, there are three ways to partition a disk:
by using the Setup program provided by the operating system, which
typically invokes its native partitioning utility; by using that
partitioning utility manually; or by using a third-party partitioning
utility such as PartitionMagic.

For better control, we partition disks manually rather than allowing
the operating system Setup program to make partitions for us. Setup
may make the same choices about partition sizes and types that we
would have made ourselves, but then again it may not. You can use the
fdisk utility from Windows 9X to partition a disk
that will boot Windows 9X or Windows NT/2000/XP. To do so, boot a
Windows Startup Disk that contains

fdisk.exe
(and

format.com , which you'll
need later) and take the following steps:

At the DOS prompt, type fdisk and press Enter to
start the partitioning utility. If you are using the original Windows
95 fdisk, the main menu appears immediately. If
you are using the Windows 95 OSR2 or Windows 98
fdisk, a preliminary screen appears to notify you
that your disk is larger than 512 MB and that this version of
fdisk has enhanced support for large hard disks,
which is incompatible with Windows NT 4.0 and Windows 95 and earlier.
Choose Yes to use this hard disk support, or No if you plan to
install one of these earlier operating systems.

If you use the original Windows 95 fdisk (or choose not to enable large disk support with a later version of fdisk), the largest primary partition you can create is 2 GB. Although you can create an arbitrarily large extended partition, logical volumes within that extended partition can be no larger than 2 GB. Later Windows 9X versions up to and including Windows 98SE include a version of fdisk that does not recognize the full capacity of disks larger than 64 GB. Windows Me fdisk does not have this limitation. For further information, see document Q263044 at http://support.microsoft.com. You can download an updated version of fdisk for Windows 98 and 98SE from http://download.microsoft.com/download/Win98/Update/8266R/W98/EN-US/263044USA8.EXE.

If there is only one physical disk
installed, the main menu presents four choices. If more than one
physical disk is installed, a fifth option appears that allows you to
select the disk to be partitioned. Note that fdisk numbers the first
physical disk as 1 rather than 0. If necessary, use option 5 to
select the disk to be partitioned.

Use option 4, Display partition information, to view existing
partitions, if any. If necessary, use option 3, Delete partition or
Logical DOS Drive, to remove existing partitions and free up space
for new partitions. Deleting a partition destroys all data on that
partition, so be sure that's really what you want to
do before you do it.

From the
main menu, choose option 1, Create DOS partition or Logical DOS
Drive, to begin partitioning the disk. fdisk displays the Create DOS
Partition or Logical DOS Drive submenu with option 1, Create Primary
DOS Partition; option 2, Create Extended DOS Partition; and option 3,
Create Logical DOS Drive(s) in the Extended DOS Partition.

To create a primary partition, choose
option 1. By default, fdisk creates the largest primary partition it
can in the available space, and marks that partition Active (or
bootable). Depending on the size of the disk and whether you enabled
large disk support, that partition may or may not occupy all
available disk space. If you override the default to create a smaller
primary partition, note that fdisk does not automatically mark that
partition active. Return to the main menu and choose option 2, Set
active partition, if you want that primary partition to be bootable.

To create an extended partition
for the remaining disk space (or for the entire disk if it has no
primary partition), display the Create DOS Partition or Logical DOS
Drive submenu and choose option 2, Create Extended DOS Partition.
Allocate some or all of the available disk space to the extended
partition (remember that you can have at most one extended partition
on the disk) and then return to the Create DOS Partition or Logical
DOS Drive submenu.

Choose option
3, Create Logical DOS Drive(s) in the Extended DOS Partition, to
create logical drives within the extended partition.

Restart the computer to put the
partitioning changes you have just made into effect.

Different versions of fdisk support
some or all of these undocumented command-line switches:

Re-creates the master boot record. This process is nondestructive on
Windows systems (it will wipe out lilo on a Linux system) and
sometimes can salvage a disk that no longer boots. Using
fdisk /mbr replaces the MBR executable code but
does not change partitioning data. Most partition sector viruses
replace or modify MBR code, so using fdisk /mbr is
a fast, easy way to rid a system of a partition sector virus.

Saves partitioning information to the file

partsav.fil .

Prevents fdisk from rebooting the system automatically upon exit.

Creates primary partition of <size> MB on disk number <#>.

Creates extended partition of <size> MB on disk number
<#>.

Creates logical volume of <size> MB on disk number <#>.

The partitioning tool we use is PartitionMagic from PowerQuest
(http://www.powerquest.com). In
addition to standard partitioning functions, PartitionMagic does
things no other partition utility we know of can do, including
changing the sizes of partitions and converting a partition from one
filesystem to another on the fly. If you frequently install or
repartition hard disks, you need a copy of this utility in your
toolkit.

14.6.3 Logical Formatting

After you
partition the disk to create logical volumes, the next step is to
format each volume, which creates the filesystem structure that will
organize the data stored on that volume. This

logical
format writes information to disk that is needed by the
filesystem, including:

A
partition boot sector for the filesystem that
occupies that partition. Don't confuse the partition
boot sector with the MBR. Information contained in the MBR applies to
the entire physical disk drive, while information contained in the
partition boot sector applies only to the partition to which it is
written.

The
System ID Byte, which identifies the partition
type and the filesystem used to format it.

Bad-sector mapping information.

Various information specific to the filesystem, including disk-free
and disk-used data and the location of files and folders within the
partition.

In the DOS/Windows 9X environment, the filesystem you create will be
one of the following.

14.6.3.1 FAT16

MS-DOS and the initial release of Windows 95
support only the FAT16 filesystem. FAT16 uses 16-bit addressing,
which limits it to 65,536 discrete addresses. If FAT16 addressed
individual sectors, it could access only (65,536 sectors x
512 bytes/sector = 33,554,432 bytes), or 32 MB. To get around this
small limit, FAT addresses clusters rather than
individual sectors. A cluster is a group of sectors. The number of
sectors/cluster is always a power of two, is constant within a
volume, and is determined automatically based on the size of that
volume. Table 14-1 lists the cluster sizes that
FAT16 uses for various partition sizes.

The downside to using clusters is that a cluster is the smallest
addressable unit on the volume, so each file must occupy at least one
cluster, and every file on average wastes half a cluster. This means,
for example, that storing a 1-byte file on a FAT16 volume larger than
1 GB requires 32,768 bytes of disk space, and that storing a
32,769-byte file requires 65,536 bytes of disk space.

This allocated but unoccupied and unusable disk space is referred to
as slack space. Large FAT16 volumes with many files have a lot of it.
For example, a 1+ GB FAT16 volume with 15,000 files, each of which
will average half a 32 KB cluster wasted, has (15,000 x
16,384), or 245,760,000 bytes of slack space.

FAT16 is the lingua franca of DOS/Windows operating systems. Any
Microsoft operating system (and many non-Microsoft ones) can read and
write FAT16 volumes. Windows 95 and later and Windows NT/2000 support
slightly modified versions of FAT16 called VFAT, which support long
filenames.

14.6.3.2 FAT32

The hard limit of 2 GB on FAT16 volume size
and the huge waste on large volumes led Microsoft to introduce the
FAT32 filesystem with Windows 95 OSR2. Microsoft really should have
called it FAT28 because four of the 32 address bits are reserved.
Using 28-bit addressing, FAT32 addresses up to 268,435,456 sectors or
clusters. Addressing individual sectors, FAT32 can access
(268,435,456 sectors x 512 bytes/sector = 137,438,953,472
bytes), or 128 GB. In fact, though, FAT32 does not use individual
sector addressing, simply because the overhead involved in managing
so many small disk space allocation units would significantly degrade
performance. Instead, FAT32 continues to use cluster-based
addressing, but with much smaller cluster sizes than FAT16. Table 14-2 lists the cluster sizes that FAT32 uses for
various partition sizes.

The smallest FAT32 partition you can create with the fdisk and format
utilities is 512MB, unless you use undocumented command-line
switches, which are undocumented for good reasons. You can convert
FAT16 volumes smaller than 512 MB to FAT32 by using the Windows 98
conversion utility or PartitionMagic, but there is little reason to
do so because FAT32 benefits only large volumes.

FAT32 also eliminates the limitation on root directory entries, which
allows you to store as many files and directories in root as you
wish. Standard DOS applications are still limited to accessing files
no larger than 2 GB, and Win32 applications to accessing files no
larger than 4 GB.

There are some drawbacks to using FAT32. First, because FAT32 uses
more but smaller clusters, file access on FAT32 volumes should
theoretically be slower than on FAT16 volumes. We tested this by
creating same-size volumes formatted for FAT16 and FAT32, restoring a
standard file set, defragmenting the volume, and then running various
disk benchmark programs. In each case, the performance of the FAT32
volume was 3% to 5% slower than that of the FAT16 volume. With equal
volume and cluster sizes, there is little discernible difference
between FAT16 and FAT32.

A more important consideration for many people is that FAT32 is
supported only by Windows 95 OSR 2.X, Windows 98, Windows 2000/XP,
and Linux. This means that on a system that dual-boots Windows 9X
using FAT32 volumes and Windows NT 4 using NTFS volumes, neither
operating system can access the other's volumes. The
shareware product WinImage (http://www.winimage.com) allows Windows NT 4
to open FAT32 partitions directly, as does the Sysinternals utility
FAT32 (http://www.sysinternals.com/ntw2k/freeware/fat32.shtml).

Windows 95 OSR 2.X and Windows 98 include FAT32-aware versions of the
fdisk, format, defrag, and scandisk utilities, which can be used for
either FAT16 or FAT32 partitions. Note, however, that DriveSpace3
compression does not support FAT32 partitions. The same is true of
third-party disk utilities that predate FAT32. Attempting to use them
on a FAT32 volume will at best not work, and may destroy your data.
Most pre-FAT32 applications can reside on a FAT32 partition without
difficulty, as can their data. Note that some pre-FAT32 device
drivers, particularly DOS block-mode drivers such as aspidisk.sys
(used to access SCSI drives without enabling BIOS support) do not
work properly from FAT32 partitions.

To further complicate matters, Microsoft created an enhanced form of
FAT32 called FAT32X to allow FAT32 partitions to extend beyond 1,024
translated cylinders, which means any drive larger than 8 GB. FAT32X
partitions use a different filesystem flag in the partition table,
and manipulating FAT32X partitions requires using methods that differ
from those used for FAT32. The fdisk and format utilities included
with Windows 95 OSR 2.X and Windows 98 automatically create FAT32X
partitions on drives larger than 8 GB, and most computer vendors
supply systems with large drives already formatted as FAT32X. Other
than the bundled DOS/Windows utilities, the only utility we know of
that can manipulate FAT32X partitions is PartitionMagic
4.0+.

14.6.3.3 NTFS

The native filesystem
of Windows NT/2000/XP, NTFS places effectively no limits on the sizes
of partitions, volumes, and files. NTFS is faster, more robust, and
more secure than any FAT filesystem. If your computer runs Windows
NT/2000/XP, there are only two reasons not to use NTFS. The first is
that because only Windows NT/2000/XP (and, of course, Linux) can
access NTFS volumes, using NTFS in a dual-boot environment means that
the other operating system will not be able to access the NTFS
volumes.

Second, there is a paucity of disk diagnosis and repair utilities
available that are NTFS-aware. For a long time, Microsoft recommended
creating a small FAT partition as the system partition from which NT
would boot, and devoting the rest of the disk to one or more large
NTFS partitions. Microsoft's thinking was that if
there was a problem on the NTFS boot partition, you might still be
able to get the system booted so that you could run a disk diagnostic
utility. In practice, doing this doesn't accomplish
much.

Although the Windows 2000/XP Recovery Console is a useful utility, it
does not always allow you to recover from problems. For that reason,
we generally configure our Windows 2000/XP systems to dual-boot two
copies of the same operating system. By that, we mean that you should
install your main Windows NT/2000/XP installation on one large NTFS
volume, and install a second minimal Windows NT/2000/XP installation
on another NTFS volume, ideally on a different physical drive. If the
main installation fails to boot, you can boot to the other copy of
Windows NT and use it to recover important data and configuration
files from the main Windows NT installation before you attempt other
recovery procedures. If all else fails, you can physically remove the
unbootable drive from the problem system and install it as a
secondary drive in a different Windows 2000/XP system, which may
allow you to recover critical datafiles from the problem drive.

Three NTFS versions exist. NT 4 uses NTFS4. To add enhanced filesystem capabilities such as user quotas in Windows 2000, Microsoft upgraded NTFS4 to NTFS5. When XP was released, it included a minor variation of NTFS5, called NTFS5.1. As we found by sad experience when installing Windows 2000 in dual-boot mode on a system already running NT 4, Windows 2000 Setup converts any local NTFS4 volumes it finds to NTFS5, which means NT 4 can no longer read, write, or boot from those volumes unless SP4 or higher is installed. Even with SP4 or higher installed, NT 4 chkdsk cannot repair NTFS5 volumes. The only way we know to repair NTFS5 volumes under NT 4 is to use the third-party utility NTFSCHK (http://www.sysinternals.com/ntw2k/freeware/NTFSCHK.shtml).

14.6.3.4 Formatting with Windows 9X

Windows 9X provides several ways to
perform a logical format. You can use the fdisk and format utilities
on a Windows 9X Startup Disk to partition and format a hard disk
before installing Windows 9X. Once Windows 9X is installed, you can
perform a logical format by right-clicking a volume in My Computer or
Windows Explorer and choosing Format, or by using the command-line
format utility. Command-line format uses the syntax
format
<drive:>
/switches, where <drive:>
is the drive letter assigned to that volume, and the available
switches that pertain to hard disk formatting are as follows:

Specifies the volume label.

Specifies that format should perform a
"quick" format, which reinitializes
the filesystem but does not perform an actual format. Using this is a
fast way to delete all data on a drive.

Tests clusters that are currently marked bad.

Copies system files to the disk being formatted, making it bootable.

Unlike the Windows NT command-line format utility, the Windows 9X
utility does nothing that you can't do using the
graphical utilities, so there is little reason to use it. For
flexibility, we prefer to use PartitionMagic to partition and format
a drive before installing Windows 9X.

14.6.3.5 Formatting with Windows 2000/XP

Windows 2000/XP provides several
methods to perform a logical format. During Setup, Windows 2000/XP
allows you to format existing or newly created volumes as either FAT
or NTFS. Other than using a third-party utility such as
PartitionMagic, this is the only method available to format an NTFS
volume before Windows 2000/XP has been installed. The format process
invoked during Setup is not very flexible, so we prefer to use
PartitionMagic to create and format partitions before installing
Windows 2000/XP.

Once a system is bootable under Windows 2000/XP, you can also perform
a logical format on a disk by using the graphical Disk Management
utility (Computer Management Storage
Disk Management), by right-clicking a volume in My
Computer or Windows Explorer and choosing Format, or by using the
command-line format utility. The first two methods allow you to
select all format options, but limit your choice of allocation unit
(cluster) size. Command- line format provides complete flexibility in
choosing cluster size, and uses the syntax format
<drive:>
/switches, where <drive:>
is the drive letter assigned to that volume, and the available
switches that pertain to hard disk formatting are as follows:

Where <file-system> specifies the
type of the filesystem to be used, and may be FAT or NTFS.

Specifies the volume label.

Specifies that format should perform a
"quick" format, which reinitializes
the filesystem but does not perform an actual format. Using this is a
fast way to delete all data on a drive.

Specifies that files created on this volume will be compressed by
default.

Specifies the allocation unit size to be used for this volume:

NFTS supports <cluster-size> 512,
1024, 2048, 4096, 8192, 16K, 32K, or 64K, but compression is
supported only on volumes that use
<cluster-size> 4096 or smaller.

FAT supports <cluster-size> 8192,
16K, 32K, and 64K, all using 512-byte sectors, and 128K and 256K
using nonstandard 1K and 2K sectors. FAT cluster sizes larger than
32K are unique to Windows NT and are not accessible by other
operating systems that support FAT. FAT requires that the total
number of clusters on a volume be less than 65,527. FAT32 requires
that the total number of clusters on a volume be greater than 65,526
and less than 268,435,446.

In general, there are enough potential gotchas in using nonstandard
cluster sizes that you should avoid using the command-line format
utility to create nonstandard cluster sizes, and instead use the
default cluster size proposed by one of the other Windows NT
formatting methods.

Note that although Windows 2000 cannot format a partition greater than 30 GB using FAT32, it can use larger FAT32 partitions that were created with Windows 98/Me. Bizarrely, Microsoft states that this behavior is by design. For further information, see Knowledge Base articles Q277546 and Q184006. Windows XP also has some FAT32 limitations, which are discussed in articles Q314463 and Q310525. You can retrieve these articles from http://support.microsoft.com.

14.6.3.6 Converting a FAT16 volume to FAT32

There are few circumstances in which
converting an existing FAT16 volume to FAT32 makes sense, but there
are a couple of ways to do it if the need arises.

To use the bundled Windows 98 utility, choose Start
Programs Accessories
System Tools Drive Converter
(FAT32). Drive Converter converts FAT16 to FAT32, but not the
converse, so be absolutely sure you want to take this step before you
start the program. If you change your mind later,
you'll have to repartition and reformat the drive to
revert to FAT16. Converting to FAT32 (or attempting to do so) may
cause the following problems:

Although the bulk of the Windows NT 4 files may reside on a separate
partition, Windows NT boots from the FAT16 partition. If you convert
that partition to FAT32, Windows NT will not be able to access it and
cannot boot.

Because Windows 98 is the only current version of Windows that can
access FAT32 partitions, converting a volume to FAT32 means that you
can run only Windows 98 or higher on that partition.

Most applications do not care whether they are running on a FAT16 or
FAT32 volume. A few, howevernotably, disk utilitiesdo
not operate or operate improperly on a FAT32 volume. Drive Converter
attempts to detect incompatible applications, and notifies you before
doing the conversion if it finds such programs, but this feature
cannot be depended upon absolutely to identify problem applications.

FAT32 does not play nice with some computers whose BIOSs support
hardware hibernation. Usually, the worst that happens is that the
hibernation feature is turned off, although we have received a couple
of anecdotal reports of systems that, after going to sleep, refuse to
access the hard disk when they awaken.

Older Windows drive compression methods, including DriveSpace3, are
incompatible with FAT32 volumes. If you convert a volume to FAT32,
you will no longer have the option of compressing it. A drive that is
already compressed cannot be converted to FAT32.

PartitionMagic 4.0 or later can convert FAT16 to FAT32 and vice
versa.