3 Starting out with VirtualBox
Note: Choose this setting carefully! The memory you give to the VM will
not be available to your host OS while the VM is running, so do not specify
more than you can spare. For example, if your host machine has 1 GB of
RAM and you enter 512 MB as the amount of RAM for a particular virtual
machine, while that VM is running, you will only have 512 MB left for all the
other software on your host. If you run two VMs at the same time, even more
memory will be allocated for the second VM (which may not even be able to
start if that memory is not available). On the other hand, you should specify
asmuch as your guest OS (and your applications) will require to run properly.
AWindows XP guest will require at least a few hundred MB RAM to run properly,
and Windows Vistawill even refuse to install with less than 512 MB. Of course,
if you want to run graphics-intensive applications in your VM, you may require
even more RAM.
So, as a rule of thumb, if you have 1 GB of RAM or more in your host computer,
it is usually safe to allocate 512 MB to each VM. But, in any case, make sure
youalways have at least 256-512 MB of RAM left on your host operating system.
Otherwise you may cause your host OS to excessively swap out memory to your
hard disk, effectively bringing your host system to a standstill.
As with the other settings, you can change this setting later,after you have cre-
ated the VM.
3. Next, you must specify a virtual hard disk for your VM.
There are many and potentially complicated ways in which VirtualBox can pro-
vide hard disk space to a VM (see chapter 5,Virtualstorage, page 75 for details),
but the most common way is to use a large image file on your “real” hard disk,
whose contents VirtualBox presents to your VM as if it were a complete hard
disk.
The wizard presents to you the following window:
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