Client virtualisation meets many needs -- security sandboxing, development, client lockdown, access to platform-locked applications or content, and safe remote access, to name but a few.

But it is accepted that client software virtualisation is too slow and resource-hungry to be of practical use to professionals. As a result, client virtualisation has gone virtually nowhere.

What if an OS running inside a virtual machine could perform at nearly the same speed as on the native hardware? That’s the boast of Parallels, whose x86 client virtualisation solutions -- Parallels Workstation 2.1 for Windows and Linux, and Parallels Desktop for Mac -- are the first commercial solutions to implement hypervisor technology.

Parallels was also the first to leverage Intel and AMD on-CPU virtualisation acceleration. With the hypervisor and CPU acceleration combined, Parallels makes good on its native performance boast -- and then some.

Parallels’ hypervisor-based solution is tuned for speed and low-latency user interaction. On an Apple MacBook Pro with a 2.16GHz Core Duo CPU, my test machine, Windows XP SP2 rockets from cold boot to desktop, with the wait cursor gone, in twelve seconds, and launches common apps instantaneously.

The secret in the sauce is that hypervisor bypasses layers that other virtualisation software must slog through every time a guest OS needs access to hardware. Parallels Desktop and Workstation not only improve on software virtualisation’s characteristically sluggish disk and network I/O, they make the virtual-to-physical (and, in the case of disk access, logical) boundary disappear.

Native performance? Confirmed. And wrap your mind around this: Parallels can sometimes outgun native performance.

Parallels Desktop and Workstation accelerate network I/O to a level I thought impossible. With Windows XP on the MacBook Pro, Internet Explorer 6 finishes loading the complex home page faster than Apple’s native Safari browser.

Overall interaction with remote Windows file shares is faster in a Parallels Desktop VM than in OS X. Here, too, the hypervisor’s bypass from the guest OS to the hardware seems magical.

Parallels Desktop and Workstation do not transcend, however, the poor GUI performance common to all client software virtualisation.

Parallels’ virtual graphics driver mimics an unaccelerated frame buffer. The product repaints only changed portions of the screen, as other solutions do, so menus and new windows snap onto the screen. But when the user forces continuous repainting of large display regions by scrolling in a browser or dragging windows around, performance suffers.

As I said, IE in a Parallels VM does load some pages faster than Safari, but scrolling within the browser, especially on pages containing Flash animation, is slow.

Parallels Desktop and Workstation are easy to set up. The only information required to create a new virtual machine is the size of the virtual machine’s RAM and virtual hard drive. After that, you can insert your guest OS’s install media and click Parallels’ Play button to boot your new, empty VM.

You can easily attach and detach virtual hard drives and CD/DVD drives, and Parallels’ software provides a USB 1.1 gateway with full auto-connect support: Attach a new USB device, and a Windows XP guest will see it and load its driver instantly. USB 2.0 support would be ideal, but having USB at all is a win.

Parallels built its products for speed and low cost, which exacts a toll in configurability. VMware Workstation, for example, handily out-features Parallels’ offerings with its capability to allow changes made during a session to be erased when the session closes (undo drives). Server-grade features are not Parallels’ forte.

Parallels Desktop and Workstation come with some utilities that you’ll quickly find indispensable. A disk image utility can grow and shrink virtual disks, and convert images from “grow as needed” to fixed-size and vice-versa. Parallels Compressor operates with one click or invokes itself on a set schedule.

It cleans and optimises Windows virtual drives of unnecessary files and defragments them. Compressor can truncate a “grow as needed” image after it’s cleaned to save disk space.

Parallels Desktop for Mac and Workstation for Windows and Linux run virtually any x86 OS you throw at them, and Parallels supplies post-install drivers for most common OSes that aid display performance and supply a few other tweaks.

Used with the hypervisor alone, Parallels’ client virtualisation solutions outperform VMware Workstation and Microsoft Virtual PC. But with Intel or AMD on-chip virtualisation acceleration enabled, Parallels Desktop and Workstation create the kind of virtual machines that you can leave running constantly. That’s what professionals have been waiting for.


Parallels Workstation and Desktop equip Windows, Linux, and OS X with the fastest client virtualisation yet seen. Parallels’ thin hypervisor layer is key, and with Intel or AMD on-CPU virtualisation acceleration turned on, Desktop and Workstation really take off. CPU, disk, and network performance are exceptional and meet, and in some ways can exceed, the vendor’s claim of native speed. Parallels has created a new class of virtualisation.