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2008-04-06 18:06:02
Traditional software licensing models are being derailed by virtualization and multicore processors. Alternative licensing schemes range from the familiar, like open source and SaaS, to untested models like pricing based on memory or virtual cores. Most server software is still licensed per socket or per CPU, which essentially mean the same thing. The reasoning is simple: Chips are easy to count and unlikely to change during the life of a server, and these licenses give IT a strong incentive to use the most powerful multicore chips available. But then, getting the most out of software has always required high-performance hardware. The only difference is that Intel and Advanced Micro Devices are now more likely to boost performance by increasing cores than increasing megahertz.
Per-chip licensing makes sense for software that runs on clearly defined hardware. This used to mean every OS and most apps, but virtualization changes all that by adding a hypervisor that shields the OS from the underlying hardware. VMware has also adopted per-socket licensing, as have open source hypervisor vendors XenSource (acquired by Citrix Systems) and Virtual Iron.
Microsoft treats each VM as a physical server with the same number of sockets as the underlying hardware. On its own, this would be a powerful deterrent to virtualization. Higher-end versions of Windows Server 2003 include licenses for extra virtual instances of the software on the same CPU--one on the Standard Edition, four on the Enterprise Edition, unlimited on the Datacenter Edition. The same will apply to Windows Server 2008. All Microsoft server licenses also include downgrade rights, meaning a virtual instance can be replaced by Windows 2000 or Windows NT.
Although Microsoft announced that it would unbundle the Hyper-V technology from Windows Server, a change from its previous claims that Viridian is an integral part of Windows Server 2008, the two are still designed to work together, and customers who choose to buy the server without it save only $28. Hyper-V represents a challenge to VMware; Microsoft already competes with hypervisors through Virtual Server 2004, a free tool that can run other operating systems on top of Windows Server 2003, rather than alongside it. At present, however, Virtual Server supports only Windows as guest OSes, though Microsoft has said it will support SUSE Linux.
BEA Systems is thus far the only vendor to abandon per-socket licensing, albeit only for LiquidVM, a virtualized Java platform that cuts out the OS and runs directly on VMware. LiquidVM is licensed per instance, regardless of whether a VM runs in a few spare CPU cycles or consumes all the resources in a cluster. This model looks relatively easy to game and likely will be attractive to very large customers. IBM and Oracle have moved in the opposite direction from BEA, counting individual CPU cores.
Subcapacity licensing can result in savings, but only if VMs are tightly constrained to a limited number of cores. Problem is, the greatest selling point of virtualization is its flexibility, enabling capacity to be moved around between VMs as loads demand. To take advantage of this attribute, every application needs to be licensed for every core that it might run on, something IBM admits will entail higher costs for most customers.
Oracle's licensing is simpler than IBM's, based on counting cores as fractions of a processor, but it's less virtualization-friendly. An Oracle database running on VMware must be licensed for every core on the underlying hardware--regardless of how many cores the VM actually runs on. At present, the only way to save on Oracle licensing through virtualization is to limit the processor cores available to a database through Solaris Containers, which Oracle sees as placing tighter limits than VMware when it comes to restricting the number of cores available to an application.
With virtualization and multiple cores making per-server pricing obsolete, vendors are taking a look at several alternative schemes. The most well-known is metered pricing, which isn't new at all--IBM has offered it on mainframes for more than 40 years, and it still accounts for 10% of all IBM's software revenue. The model is generally more akin to a cell phone plan than strict metering: A fixed fee includes a certain amount of computing power, with customers paying extra when this cap is exceeded. It also isn't limited to software, as the bill is for the underlying hardware, too.
Before it was acquired by Oracle, PeopleSoft had the most egalitarian system, a proprietary equation that accounts for a customer's industry, head count, and revenue.
Most Linux distributions now include a Xen hypervisor, but vendors are split on how they handle licensing for instances that run on top of it. Novell lets customers run any number of instances inside VMs, with payment based on the underlying number of CPUs. Red Hat follows the same model as Sun, requiring a separate license for each installation unless customers use its built-in virtualization technology.
