Feeds

Cheap as chips: The future of PC virtualisation

Playing catch-up

Secure remote control for conventional and virtual desktops

A brief history of virtualisation VMware was founded in 1998, and until the launch of its eponymous product the next year, the PC’s x86 architecture had been considered to be impossible to fully virtualise.

Since that time, although VMware continues to prosper, prices of virtualisation tools have fallen to an all-time low – in fact, most hypervisors are free, with just the management tools costing money.

The canny are therefore asking if or when the bubble is going to burst. It looks like the classic hype cycle: following the "peak of inflated expectations" comes the "trough of disillusionment."

Some of the key weaknesses of current x86 virtualisation methods and technologies can be revealed by comparing PC hypervisors with those on mainframes and large Unix servers.

Partitioning

For instance, compared to mainframe partitioning, if you use a full PC server OS to run full-system VMs containing other full server or client OSs, the result is horribly inefficient.

Whole layers of the software stack are duplicated on both host and inside multiple VMs. It doesn’t even make a huge difference if the host runs Linux and the guests Windows, or the other way round – either way, there is functional duplication in the stack.

On an x86 server with guest OSs running under a hypervisor, a full copy of Windows (say) is running on an emulated chipset connected to emulated disk drives (formatted with a normal filesystem), and talking through emulated Ethernet cards to another real operating system – which is storing the VM images in another filesystem running on a real disk.

If you’re running current or recent Windows guests under a Windows 2008 Server R2 with Hyper-V, then the Enlightened I/O drivers allow for dynamic memory sizing and reasonably efficient driver communication between guests and host – but there is still a lot of duplicated code, which is both wasteful and inefficient.

It means VMs run more slowly and take more disk space and memory. It also means that all the OSs in the stack must be patched and updated separately.

If you have half a dozen Windows servers running in VMs, then that is half a dozen copies of Windows that must be updated – and possibly a host copy as well. Even if tools such as WSUS ease the deployment, it still has to be done.

On the other hand, if the guests are running under VMware ESX or XenServer, then the host OS is relatively simple and lightweight, but the guests are running under pure software emulation of complete systems – in VMware's case, complete with emulation – albeit heavily-optimised – of the host CPU for running Ring 0 code. This means a significant amount of emulation overhead.

A lot of duplicated code, which is wasteful and inefficient

Let’s consider what could be eliminated. In part three of this series, we looked at the Unix way of doing things: OS-level virtualisation. This means that only the userland of the OS is virtualised, with multiple userlands running atop a single kernel. One installed copy of the OS can appear to be dozens or more – but all sharing the same core binaries, the same memory and real native unvirtualised CPUs.

Parallels’ Virtuozzo Containers brings this integral feature of Solaris, AIX and FreeBSD to Windows. Virtuozzo isn’t cheap, whereas Hyper-V and VMware are essentially free – but then again, half a dozen Virtuozzo VMs need no more RAM and disk than would be taken by installing all the apps in them straight on the host OS. The savings can be very considerable indeed, and the host server’s resources are shared equally by all the VMs – no partitioning or allocation is required.

Beginner's guide to SSL certificates

More from The Register

next story
Xperia Z3: Crikey, Sony – ANOTHER flagship phondleslab?
The Fourth Amendment... and it IS better
Don't wait for that big iPad, order a NEXUS 9 instead, industry little bird says
Google said to debut next big slab, Android L ahead of Apple event
Microsoft to enter the STRUGGLE of the HUMAN WRIST
It's not just a thumb war, it's total digit war
Ex-US Navy fighter pilot MIT prof: Drones beat humans - I should know
'Missy' Cummings on UAVs, smartcars and dying from boredom
Netscape Navigator - the browser that started it all - turns 20
It was 20 years ago today, Marc Andreeesen taught the band to play
A drone of one's own: Reg buyers' guide for UAV fanciers
Hardware: Check. Software: Huh? Licence: Licence...?
The Apple launch AS IT HAPPENED: Totally SERIOUS coverage, not for haters
Fandroids, Windows Phone fringe-oids – you wouldn't understand
Apple SILENCES Bose, YANKS headphones from stores
The, er, Beats go on after noise-cancelling spat
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
Three 1TB solid state scorchers up for grabs
Big SSDs can be expensive but think big and think free because you could be the lucky winner of one of three 1TB Samsung SSD 840 EVO drives that we’re giving away worth over £300 apiece.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.