Virtualisation's dirty little secret

David M Williams
Tuesday, 17 February 2009 04:06

IT Industry - Market

That's right; your choice of CPU - multi-CPUs, multi-cores - may not make a fig of difference to your virtual machines.

Now, sure, RAID 5 hot-swappable disks and redundant power supplies and ILO will be extremely beneficial.

However, the bulk of current virtualisation software does NOT handle multi-cores or multi-processors.

If you’re a Microsoft shop and you’re looking at Microsoft’s free Virtual Server 2005 make sure you realise that each virtual machine can only see one core. That’s right; you’d need to have eight virtual machines running simultaneously on a quad-core dual-processor server before you genuinely use the processing power available.

VMWare offers more grunt here, but even so is still limited. With the free VMWare Server you can assign one core each from two processors – giving two cores max. Going up the tree to VMWare ESXi – also free – you get up to four cores.

On the one hand perhaps that’s pretty good; after all, it’s unlikely you’d run just one virtual machine on your virtual server hardware.

If your hardware goes into more CPUs and more cores you’re going to be looking at spending money. There’s no way out. The free products are limited. You will need Windows Server 2008 hypervisor edition or VMWare Infrastructure edition before you can really take advantage of the hardware you’re working with.

Perhaps this is not unexpected; how much can you really expect for free? Yet it leaves a bad taste in your mouth to have virtualisation spruiked as the solution to all infrastructure ills just to find the hyped “doesn’t cost anything!!” offerings from Microsoft and VMWare are little more than free samplers of the real experience.

And, perhaps, if you’re going to invest in a software cost just maybe your problem would be solved equally well by spending in another area.