What's the Real Story on KVM Usage?
We've talked a lot in this column about Red Hat's KVM-based virtualization, but how much is it actually being used?
Veeam's quarterly V-Index hypervisor survey gave us some idea (until it was discontinued last year), and the figures for KVM weren't that impressive: VMware, Citrix and Hyper-V accounted for 99.5% of primary hypervisor usage in the U.S., while "others," including KVM, accounted for just 0.5%.
In reality, though, KVM is probably often used by Linux admins as a secondary hypervisor to virtualize Linux systems after the Windows guys (and gals) have virtualized their systems using VMware's vSphere hypervisor or, to a growing extent, Hyper-V. In smaller organizations it's probably the same admin who is virtualizing servers running both operating systems.
"Virtualization is getting better understood, so if an admin uses (VMware's) vCenter then it won't take a lot to deploy RHEV. The concepts are the same," says Navin Thadani, Red Hat's senior director of virtualization. Red Hat Enterprise Virtualization (RHEV) is Red Hat's KVM-based virtualization product.
That means that the proportion of companies using KVM somewhere in their enterprise is bound to be higher than 0.5% — much higher, in fact. This is borne out by a recent survey carried out by Nexenta, an OpenStorage vendor, in May and June of 2012. The survey found that of the 4,000 customers, community members and developers questioned, a whopping 17.6% use KVM, and 19.1% reckon they'll be using it in the next twelve months.
The figures need to be treated with a little caution, though, as Nexenta customers and the others questioned are likely to be particularly well disposed to open source software, and the survey has a large margin of error. But it certainly indicates that KVM is being used as a secondary hypervisor to a far higher degree than you might guess from an initial look at Veeam's figures.
There's more evidence for this that comes from VKernel, a division of Quest Software that makes capacity management and performance monitoring products for virtualized data centers and cloud environments. (In July Dell announced the intention to acquire Quest Software before the end of November.)
The company offers a free tool called vOPS Server Explorer for VMware and Hyper-V environments, and at the end of September Quest Software announced it will be offering it as a RHEV virtual appliance for RHEV KVM-based environments too.
Businesses that are still in business are generally not fools, so it's a fair bet that VKernel is offering this tool because it feels the KVM market is big enough to be worth bothering about and cultivating, and ultimately because it is a market from which VKernal believes it can make money. (vOPS Server Explorer is a free taster and uses the same analytics and advisory engine as VKernel's paid-for vOPS Server Standard product that includes performance analysis, capacity management and planning, optimization and chargeback for vSphere, Hyper-V and KVM/RHEV hypervisor environments.)
vOPS Server Explorer can be used as a health monitoring tool that provides quick enterprise-wide visualization of server virtualization performance, capacity and efficiency issues and can:
- Identify critical VM configuration errors such as memory limits and old snapshots that will severely affect performance and can be especially hard to track down and solve
- Recognize performance bottlenecks from high CPU Ready (the time a virtual machine waits in the queue in a ready-to-run state before it can be scheduled to access the CPU,) memory swapping, device latency and other causes
- Detect inefficiency and waste created by VMs with CPU, memory and storage over-allocation
- Find available capacity expressed as the number of VMs that can be deployed without causing performance bottlenecks
- Pinpoint over-subscription of CPU, memory and storage resources and whether the over-allocation is impacting performance
- Search for a specific VMs using Google-like search capability
It's annoying when useful free tools are not available for the hypervisor you use, and it's also a validation of any hypervisor when free tool makers do bother to support them.
So VKernel's announcement is good news for RHEV users, and it's also a validation of KVM. VKernel — and thus Quest, and indirectly Dell — obviously believes KVM is worth devoting attention to, which probably wouldn't be true if KVM's market share wasn't both significant and growing.
Paul Rubens is a technology journalist and contributor to ServerWatch, EnterpriseNetworkingPlanet and EnterpriseMobileToday. He has also covered technology for international newspapers and magazines including The Economist and The Financial Times since 1991.
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