1. Working with Disks, Partitions, and Volumes
Before you can store data on a physical disk, you must prepare the
disk by setting a disk type, partitioning its space, assigning a drive
designator, and formatting its partitions or volumes.
After partitioning a disk, you must assign each partition or volume
a drive designator. The drive designator can be a letter or a path. You
use drive letters to access file systems in various partitions on
physical drives. Generally speaking, the drive letters A through Z are
available. However, the drive letter A is usually assigned to a
system’s floppy drive. If the system has a second floppy drive or
another removable-media drive, the letter B is usually assigned to it
(or unassigned otherwise). The drive letter C is usually assigned to
the first partition or volume created on Disk 0. The drive letter D is
usually assigned to the first CD-ROM or DVD-ROM drive. Thus, on most
systems, the drive letters E through Z are available. If you need
additional volumes, you can create them using drive paths.
A drive path is set as a folder location on an existing local disk.
For example, you could mount additional drives as C:\Docs1, C:\Docs2,
and C:\Docs3. Drive paths can be used with basic
and dynamic disks. The only restriction for drive paths is that you
mount them on empty folders that are on NTFS-formatted local disks.
Formatting a partition or a volume sets the file system that will be
used and creates the necessary file structures. In general, you can
format a partition or a volume as FAT, FAT32, or NTFS. There are
restrictions and requirements for the use of each, however.
FAT, also referred to as FAT16, is a 16-bit file system designed to
be used with volume sizes of up to 4 GB. FAT uses a boot sector that
stores information about the disk type, the starting and ending
sectors, and the active partition. FAT gets its name from the file
allocation table it uses to track the cluster locations of files and
folders. There is a primary table and a duplicate table. The duplicate
is used to restore the primary table if it becomes corrupted. FAT also
has the capability to mark clusters (sections of disk containing data)
as unused, in use, bad, or reserved. This helps to make FAT a fairly
robust file system. FAT is best with volumes of 2 GB or less, and it
has a maximum file size of 2 GB. FAT can also be used with floppy disks
and removable disks.
FAT32 is a 32-bit version of FAT16, with some additional features
and capabilities. Like FAT16, FAT32 uses a primary and a duplicate file
allocation table. FAT32 can also mark clusters as unused, in use, bad,
or reserved, and it too can be used with removable disks. FAT32 has a
minimum volume size of 33 MB, a maximum volume size of 32 GB, and a
maximum file size of 4 GB. exFAT is an enhanced, 64-bit version of FAT.
To retain the speed and other advantages of FAT, use exFAT for
volumes larger than 32 GB. Windows 8 supports exFAT on both internal
and external volumes.
Note
The 4-GB maximum file-size limitation for FAT32 is specific to
Windows 2000 and later versions of Windows. With FAT32, some earlier
versions of Windows can create larger volumes, as can other operating
systems.
NTFS is very different from FAT. Instead of using a file allocation
table, NTFS uses a relational database to store information about files
and folders. This database is called the master file table (MFT), and it stores a record of each file and folder on a volume,
as well as additional information that helps to maintain the volume.
Overall, the MFT makes NTFS much more reliable and recoverable than
FAT16 or FAT32. NTFS can recover from disk errors more readily than
FAT16 and FAT32 can, and NTFS generally has fewer disk problems.
Some, but not all, of this resiliency is built into exFAT, which
uses transactions to improve reliability and recoverability. Both NTFS
and exFAT have a maximum volume size of 256 TB with standard format
disks and a maximum file size that is limited only by the volume size.
Although you can’t use NTFS or exFAT with floppy disks, you can use
NTFS and exFAT with removable disks. Additionally, unlike FAT16 and
FAT32, which have limited security features (namely that you can mark a
file only as read-only, hidden, or system), exFAT supports basic access
controls. Only NTFS has advanced security that lets you use permissions
to set specific file and folder access, however, and only NTFS supports
other advanced features like compression, encryption, and disk quotas.
fsutil fsinfo ntfsinfo c
:,
where c: is the designator of the drive you want to work with. If the internal NTFS version is listed as 3.1, you’re actually working with NTFS 5.1.
2. Using Disk Mirroring
With disk mirroring, you use identically sized volumes on two
different drives to create a redundant data set. The drives are written
with identical sets of information, and if one of the drives fails, you
can still obtain the data from the other drive.
Although disk mirroring offers fault tolerance, the major drawback
to disk mirroring is that it effectively cuts the amount of storage
space in half. For example, to mirror a 500-GB drive, you need another
500-GB drive. That means you use 1,000 GB of space to store 500 GB of
information.
Creating Mirrored Volumes
You create a mirror set by following these steps:
-
In the Disk Management Graphical view, press and hold or right-click
an area marked Unallocated on a disk, and then tap or click New
Mirrored Volume. This starts the New Mirrored Volume Wizard. Read the
Welcome page, and then tap or click Next.
-
The key difference is that you must create two
volumes of identical size, and these volumes must be on separate
drives. You won’t be able to continue past the Selected Disks window
until you select the two disks that you want to work with.
-
As with other RAID techniques, mirroring is transparent to users.
Users see the mirrored set as a single drive that they can access and
use like any other drive.
Note
The status of a normal mirror is Healthy. During the creation of a
mirror, you’ll see a status of Resynching, which tells you that Disk
Management is creating the mirror.
Rather than create a new mirrored volume, you can use an existing
volume to create a mirrored set. To do this, the volume you want to
mirror must be a basic partition or simple volume, and you must have an
area of unallocated space on a second drive of equal or larger size
than the existing volume.
In Disk Management, you can mirror an existing volume by following these steps:
-
Press and hold or right-click the basic partition or simple volume
you want to mirror, and then tap or click Add Mirror. This displays the
Add Mirror dialog box.
-
In the Disks list, select a location for the mirror, and then tap or
click Add Mirror. Windows 8 begins the mirror creation process. In Disk
Management, you’ll see a status of Resynching on both volumes. The disk
on which the mirrored volume is being created has a warning icon.
You may want to or need to break a mirrored set. For example, if you
no longer want to mirror your drives, you can break a mirror, which
allows you to use the disk space for other purposes. If one of the
mirrored drives in a set fails, disk operations can continue, but at
some point you’ll need to fix the mirror, and to do this you must break
the mirror and then reestablish it. Although breaking a mirror doesn’t
delete the data in the set, you should always back up the data before
you perform this procedure. This ensures that if you have problems, you
can recover your data.
In Disk Management, you can break a mirrored set by following these steps:
-
Press and hold or right-click one of the volumes in the mirrored set, and then tap or click Break Mirrored Volume.
-
Confirm that you want to break the mirror by tapping or clicking
Yes. If the volume is in use, you’ll see another warning dialog box.
Tap or click Yes to confirm that it’s okay to continue.
Windows 8 then breaks the mirror, creating two independent volumes.
(You don’t need to break a mirror before you remove mirroring; Windows
breaks the mirrored set as part of the removal process.)
In Disk Management, you can remove one of the volumes from a
mirrored set. When you do this, all data on the mirror you remove is
deleted, and the space it used is marked as Unallocated.
To remove a mirror, follow these steps:
-
In Disk Management, press and hold or right-click one of the volumes
in the mirrored set, and then tap or click Remove Mirror. This displays
the Remove Mirror dialog box.
-
In the Remove Mirror dialog box, select the disk from which to remove the mirror.
-
Confirm the action when prompted. All data on the removed mirror is deleted.
