Converting Basic Disks to Dynamic Disks
Up to this point everything that has been discussed in
this article has related to Basic disks, but Windows XP
professional supports another type of disk structure called
a Dynamic disk. Dynamic disks first appeared in Windows 2000
and are only compatible with Windows 2000 and Windows XP
Professional operating systems. If you're running Windows XP
Home Edition the option for Dynamic disks is unavailable.
Throughout this article we've spent a substantial amount of
time talking about primary partitions, extended partitions,
and logical drives. A Dynamic drive contains dynamic volumes
rather than partitions, making it possible to have an
unlimited number of logical drives. Another big difference
between basic and dynamic disks is there is no Master Boot
Record (MBR) on a dynamic disk. Instead, it stores the
layout of the disk volumes in a database stored on the last
1 MB of the disk. Other than the fact dynamic volumes are
used instead of partitions, why would you consider creating
or converting a basic disk to a dynamic disk? Dynamic disks
allow you to create a number of different disk structures
that aren't available on basic disks. For example;
- Simple Volume - A dynamic volume that's composed of
disk space from a single dynamic disk. Not
fault-tolerant but can be mirrored.
- Spanned Volume - A dynamic volume that uses disk
space on more than one physical disk. If there is more
than one dynamic disk the size of the spanned volume can
be increased by extending it onto the additional dynamic
disk.
- Striped Volume - A dynamic volume that stores data
in stripes across two or more physical hard drives.
Striped volumes are noted for very fast performance but
the downside, which can be substantial, is that if one
of the disks in the stripe set fails the entire volume
is lost.
- Mirrored Volume - A volume that duplicates the data
on two physical disks. The identical volumes are called
mirrors. Since the data is mirrored on a different disk,
if one disk fails the system will switch to the mirror
and remain functional. Mirrored volumes are also
fault-tolerant.
- RAID-5 Volume - This is a bit of a departure from
the other types of volumes in that it requires at least
three hard disks to implement, but basically it consists
of data and parity sets that are striped across multiple
hard disks. If one of the disks in a RAID-5 volume
fails, XP can recreate the failed portion by using the
data and parity information from the remaining disks in
the volume.
I'll be the first to tell you that dynamic disks
aren't for everybody. They have a learning curve and the
chances of screwing something up is substantially higher
than working with basic disks. Because some of the most
useful disk structures require multiple hard drives
there is the additional expense as well as the risk
associated with data loss in case of a drive failure. A
comprehensive backup strategy to media that can handle
the size of data sets that are created is essential.
Until you've experimented with dynamic disks to learn
and understand their uniqueness I wouldn't recommend
they be used to the exclusion of basic disks.
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Warning For Those
Tempted To Experiment With Dynamic Disks
More than once
I've been contacted by users that have converted
basic disks to dynamic disks and then decided
they preferred basic disks and wanted to convert
the dynamic disks back to basic disks. The
following warning comes directly from the Help
file for Disk Management from Microsoft.
"After you
convert a basic disk to a dynamic disk, you
cannot change the dynamic volumes back to
partitions. Instead, you must delete all dynamic
volumes on the disk and then use the Convert
To Basic Disk command. If you want to keep
your data, you must first back it up or move it
to another volume." |
For those that do want to experiment, the
screen captures below illustrate converting Disk 2 and 3
into a Spanned Volume. Right click on
one of the Basic Disks to be converted to a Dynamic Disk and
select [Convert to Dynamic Disk] to proceed.
Fig. 01 Select the disk or disks to be
converted. In this example I'm selecting two because they
will ultimately become a Spanned Volume. Click [OK] to
proceed.
Fig. 02
Compare Fig. 03 to Fig. 01 and note the Basic disks have
been converted to Dynamic disks. Right click in the
Unallocated space and select [New Volume...] to open the
New Volume Wizard.
Fig. 03 The New Volume Wizard is the
Dynamic Disk equivalent of the New Partition Wizard for
Basic Disks, reflecting the difference that Dynamic Disks
use volumes rather than partitions. Click [Next] to proceed.
Fig. 04 The Volume Type box contains
three choices; Simple, Spanned, and Striped. I've included
screen captures [Fig. 05, 06, and 07] of the window showing
each option selected so the Description section is available
for reading.
Fig. 05
Fig. 06
Fig. 07 Because I'm creating a Spanned
Volume the Select Disks screen appears listing the disks
that are available to become a part of the volume. In this
case, Disk 2 is selected by default and the additional
choices available are shown in the Available pane.
Fig. 08 Once the disks have been added,
select the amount of space to be allocated to the Spanned
Volume and click [Next] to proceed.
Fig. 09 Disk Management
automatically offers to assign the next available drive
letter to the new partition. Use the drop down selector to
choose a different letter.
Fig. 10 The final step is to select
the formatting options for the volume. It's not absolutely
necessary to format the volume if you're just setting up a
partition scheme that will be used later. If so, select the
first option. If the volume is formatted
at this time the drop down boxes are used to select the file
system type and allocation unit size. Unless you have a
specific reason reason to use FAT32 or change the allocation
unit the defaults will work fine. Supply a label for the
volume now (I used Spanned Example) or just accept the default. If you want to save
some time use the quick format option.
Fig. 11 Review the selected settings
[Fig. 12] and click the [Finish] button. The process will
begin immediately with no further user intervention.
Fig. 13 As Fig. 14
illustrates, the Spanned Volume, Spanned Example, has been created and added to Disk
Management, assigned drive letter H and is formatted with
the NTFS file system. Looking at the spanned volume in the
lower half of the Disk Management utility is a bit
misleading because it shows both Disk 2 and 3 as being 19.08
GB, and although this is true, both disks are now under one
drive letter (H) and the total spanned capacity of the two
drives is 38.16 GB as shown in the upper part of the Disk
Management display.
Fig. 14 Before you do anything with
Dynamic disks I suggest you read through the entire Help
section of Disk Management. There are many little caveats to
working with them that are far beyond the scope of this
brief introductory article. Even if you absorb every word of
the Help section you'll likely end up making some mistakes
that only experience will solve, but it's always better to
go into a new area with as much knowledge as possible.
Up
What Is A Partition?
One Partition or Multiple Partitions?
Partitioning A Blank Hard Drive During XP Installation
Reassigning Drive Letters
Resizing An Existing Partition On A Single Hard Drive
Creating A Primary Partition In Unallocated Space
Creating An Extended Partition And Logical Drives
Creating Logical Drives In An Extended Partition
Multiple Hard Drive System Partitioning
Converting Basic Disks to Dynamic Disks |
