User Guide

Changing Settings and Preferences
55
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About the Undoable option
When you designate a disk image as undoable, information written to
the disk image by the guest OS is not immediately written to the disk
image file itself. Rather, changes are written to a temporary file and
accumulated throughout the session.
When you shut down the virtual machine, you can choose to commit
or undo the changes. If you choose commit, the changes from the
temporary disk image are merged back into the original disk image. If
you choose undo, the temporary file is discarded, leaving the initial
hard disk image unmodified.
This feature is useful when you want to maintain the original state of
a hard disk image. It is also useful if you are running software that
may contain a virus or a disk-related bug that could corrupt the disk
image.
The temporary undo file can grow large if you make significant
changes to the drive image during the course of the session, for exam-
ple, if you install a large program on the virtual machine. Choose a
location for the undo file that has adequate space. (By default, the
location is the same directory on your host PC as the drive image you
have specified.)
Hard Disk 2 and Hard Disk 3 settings
Use the settings for Hard Disk 2 and Hard Disk 3 to control second-
ary and tertiary drive images for a virtual machine. (Hard Drive 2 and
Hard Drive 3 function as drive D and drive E, respectively, on the vir-
tual machine.) You may want to specify a Hard Disk 2 or a Hard
Disk 3 for additional storage space.
IMPORTANT
Be careful to use the Undoable option consistently
between Hard Disks. For example, if you do not set Hard Disk 1 as
undoable and then set Hard Disk 2 as undoable, this may result in
problems if you install an application on Hard Disk 2 and shut down
without committing changes (see page 43.)
NOTE
Most operating systems do not allow read-only drive images to
be assigned as secondary drives (Hard Disk 2 or Hard Disk 3).
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