Hardware Reference
In-Depth Information
Partitioning a Disk and Creating Logical Drives
An OS doesn't deal directly with the physical hard disk. Instead it deals with logical drives.
A
logical drive
is a drive letter that has been assigned to a portion of a physical disk. A
single physical disk can have multiple logical drives. The OS might see a C drive, a D drive,
and an E drive, for example, all of which are part of a single physical disk drive.
To create these logical drives, you must fi rst create
partitions
. At a minimum you need
to create one
primary partition
. You can allocate all the space on the entire physical drive,
or you can set aside some of the space for another partition. If you do set aside space, you
can create an
extended partition
and then create additional logical drives on that partition.
When you partition a physical drive, it creates a
master boot record (MBR)
that contains
information about each partition and logical drive. The OS looks to the MBR to determine
what drive letters you have.
Partitioning requires a disk management utility. Each OS comes with at least one
such utility, and third-party partitioning utilities are also available. The Windows Setup
program contains a partitioning and formatting utility and, within Windows, you can use
the Disk Management utility (from Computer Management, as you'll see in the upcoming
exercise) to partition and format drives. In earlier versions of Windows, a text-based
utility called FDISK was used to manage partitions. If you're using the Windows Recovery
Console, a similar program called DISKPART manages partitions.
A disk needs to be partitioned only once; you should repartition a drive only if you want to
change the allocation of the disk space to the various drive letters. Repartitioning a drive, in
most cases, will wipe out the current contents of the drive, so don't change the partitions on
a drive that contains data you want to keep. Some third-party partitioning programs can do a
nondestructive repartition—that is, can change the partition sizes without losing any data.
Computers that come with a hidden recovery partition are set up such that
the single hard disk is split into two partitions, one of which contains the
hidden backup files and the other of which contains the C: drive, the main
drive that you work with when you access the computer's hard disk. The
fact that there are two partitions isn't obvious until you run a recovery
utility that accesses the hidden one.
High-Level Formatting
After you create the partitions and the logical drives, the OS sees them but can't read and
write them because they haven't yet been high-level formatted. High-level formatting lays
down an organization system that is compatible with the specifi c OS installed.
In Windows XP and higher, the predominantly used fi le system is NTFS. FAT32 is an older
fi le system that is backward compatible with earlier Windows versions, such as Windows
98. For NTFS, high-level formatting entails creating a
master fi le table (MFT)
that contains
pointers to the starting points of fi les and folders. It's essentially a table of contents for the
logical drive. A
volume boot record
is also created, which stores information needed to boot
from the drive, and a
root directory
(that is, a top-level folder).
