What Is Red Hat KVM?

In a world of rapidly changing and evolving virtualization infrastructures, vendors are in constant pursuit of making them more robust, reliable, operational, and, to put it simply, overall more efficient. Kernel-based Virtual Machine (KVM) is an open-source virtualization technology that converts Linux into a bare-metal hypervisor, having all the necessary components (memory manager, process scheduler, input/output (I/O) stack, etc) as part of the Linux kernel. In comparison with most industry-leading products, KVM hypervisor offers much more flexibility for its users, leaving a lot of free room for improvement, so that migrating to KVM-based virtual infrastructure seems like actually quite a reasonable idea.

At first, the Kernel-based Virtual Machine was created and launched by a company known as Qumranet way back in 2006. KVM hypervisor was later acquired by Linux in 2007 and in 2008, Red Hat bought Qumranet. Since Red Hat KVM, like other technologies under Red Hat, is open-source, Linux launched the Open Virtualization Alliance, which included Intel, HP, IBM, and Suse. KVM software is frequently associated with QEMU. The latter emulates hardware while KVM hypervisor allocates the necessary IT resources from the host system. Thus, since Linux KVM is a part of a large and broad Linux family, it is safe to say that everything that Linux can offer KVM can offer too. But let's look more closely at the Kernel-based Virtual Machine.

Components of the KVM

KVM hypervisor is a fully functional virtualization function embedded in the Linux kernel (the core of the operating system itself) since 2.6.20 (way back in the day). Linux KVM operates on AMD 64 and Intel 64 hardware. KVM installation is quite easy. Similar to Windows Hyper-V, it has to be activated from the kernel. You can't run KVM on Windows, however, you can run Windows over KVM.

Key KVM components include:

  • VirtIO Drivers that are specialized drivers developed for the hypervisor to work with guest systems and which allow executing para-virtualization.
  • KVM Tool concludes a more lean software that's an alternative to QEMU, which is chosen depending on your environment's production requirements.
  • QEMU comprises an independent piece of software that emulates hardware components and manages virtual machines. Red Hat KVM utilizes it to emulate hardware and increases its speed thanks to para-virtualization. Most often, Linux KVM and QEMU go together in a single package and are closely connected.
  • Kernel Extension is the actual translation layer between your hardware and its virtualized counterpart generated by Linux KVM. It includes the kernel.co extension, kvm-amd and kvm-intel modules, which are used based on your existing processor brand.
  • Libvirt is the Linux KVM application programming interface (API) to operate your virtual machines (VMs). Like any other similar piece of software, it enables monitoring and managing your virtualized resources, and Libvirt also includes the VM Manager graphic user interface (GUI).

Like most Red Hat distributions, Linux KVM is quite straightforward and no-nonsense, which are the qualities that are loved by its large open-source community. Now, a brief look at what KVM can do is due.

KVM Features

First of all, like any other hypervisor, KVM hypervisor exists to enable and govern virtualization processes. It abstracts your hardware and allows running applications by using virtualized resources hosted by your KVM hypervisor servers. Red Hat KVM provides hardware for guest systems either through emulating it via software or by executing hypervisor control and allocating to real hardware resources.

For general reference, there are several types of KVM virtualization:

  • Full virtualization when your hardware is totally emulated via software and works independently in the virtualized environment without any interaction with the real, physical hardware, which renders corresponding drivers unnecessary. However, you will sacrifice performance here.
  • Para-virtualization means that your guest systems interact with your host system (the hypervisor server) to a certain extent, which means specific drivers will be necessary.
  • Hardware-assisted para-virtualization, where the process has the hardware support already integrated. Subsequently, performance is increased since everything original is already there, working directly with the processor without any intermediaries. This is usually the preferred case of operation.

While Linux KVM has all the principle standard functionality expected of a hypervisor, there is certain specificity to it being a Red Hat distribution. Using the Kernel-based Virtual Machine has its own advantages and preferences appreciated by the Linux open-source community.

Among others, Linux KVM includes the following features:

  • Automatic NUMA Balancing, which, as its name suggests, exists to enhance the performance of applications running on NUMA-based hosts.
  • Disk I/O Throttling allows you to define a limited number of I/O requests sent by a designated VM to your hosts, which can be used to improve performance.
  • Over-committing enables, if necessary, your KVM to allocate more virtualized CPU or memory resources than the available resources on your host system.
  • Thin Provisioning grants Red Hat KVM the ability to allocate flexible storage and greatly optimize the available storage space for every VM individually.
  • Virtual CPU Hot Add is a great feature that imbues your KVM with the capability to increase processing resources necessary to certain VMs without causing downtime.

Linux KVM certainly sounds like a great hypervisor, and it is. However, it can only govern existing algorithms and available resources. When it comes to fault tolerance, convenient and fast disaster recovery, exceptionally high constant application uptime, or High Availability (if necessary), the Kernel-based Virtual Machine won't be able to grant you that. However, coupled with StarWind Virtual SAN, your KVM-based hyper-converged infrastructure will show you what real power on a budget can truly mean for an Enterprise ROBO, SMB, or Edge.

Red Hat Linux KVM and
StarWind VSAN

StarWind VSAN is a useful addition to any environment since it runs as a native hypervisor component. Still, in the case with kernel-based virtual machine and KVM hypervisor specifically, their union can lead to impressive performance results:

  • As Linux KVM possesses traditional Linux performance, allowing the most demanding app loads to be virtualized, StarWind can provide highly available block storage to build HA Cluster using Linux KVM.
  • Live migration, supported by KVM hypervisor, guarantees a stable work of a VM even if relocated, and StarWind iSCSI can provide maximum bandwidth for block storage transfers, making VM migration look easy.
  • Linux KVM technology is flexible enough to utilize basically any storage supported by Linux, using multipath I/O to provide required redundancy; at the same time, StarWind VSAN manages storage to match VM workloads, so that storage performance is on top without requiring costly storage and simultaneously avoiding random I/O.

Linux KVM hypervisor is a force to be reckoned with by itself, but with StarWind VSAN, its key features can be developed to their full potential.

What is
StarWind VSAN?

For small and medium-sized businesses or ROBO, such a small step in development as building an IT infrastructure can turn out to be a severe challenge. Unlike big enterprises, not everybody can afford expensive custom hardware. However, StarWind Virtual SAN seems to be a perfect fit for such cases because it allows creating a shared storage pool with off-the-shelves hardware at minimal costs, bringing to the table a rich feature-packed stack as well. Not only would it make your environment more efficient with a minimum of resources, StarWind, working on 2 nodes, can still keep your infrastructure high available and fault-tolerant, since it keeps functionality even if one of the nodes goes off due to failure or outage.

StarWind VSAN Features and Benefits

A prime choice for small businesses, StarWind Virtual SAN, makes shared physical storage seem obsolete. While enabling your environment with outstanding performance, reliability, and fault-tolerance, this product fulfills a lot of functions with its broad feature specter. Easy in managing, configuring, and deploying, it provides you with several benefits.


By limiting the hardware footprint accompanying traditional physical storage, StarWind VSAN allows you to double your savings by lowering CapEx and OpEx. You can forget about additional licensing expenses as well. Naturally, as any product of a kind, it still requires hardware for work, but the difference in price between custom hardware and commodity one is evident enough.

Simple in Use

Running on basically every hypervisor, StarWind Virtual SAN can offer simplicity in use and configuration that hardly can be matched. You don't need specific knowledge to operate it, every admin with a standard experience of working with virtualized environments can quite easily manage, configure, and deploy StarWind VSAN.

Performance and Features

StarWind Virtual SAN provides an impressive performance level. Apart from being hardware agnostic, guaranteeing fault-tolerance of the environment, and providing high availability for application, VSAN brings to the table a set of features specifically designed for this product, such as server-side cache, LSFS, Automated Storage Tiering, etc.

Proceed to the link if you want to read more about Virtual SAN from StarWind.
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