vSAN double-node cluster

Hyper-convergence infrastructure

The hyper-convergence infrastructure means virtualization of all the conventional subsystems of the classic IT environment. As a minimum it means the virtualization of the calculation layer – hypervisor, software-defined storage, and the computer network. The virtualization ergo the software control of the regular computer units enables introducing the redundancy and thanks to it better security of the virtual machines based on the physical hardware. Hyper-convergence also means lower deployment and usage costs of the environment. Servers with the adequate number od hard disks are essential to install the service unlike in the classic approach to virtualization where the hosted machine data are stored on a separated disk array. Hyper-convergence is also the simplification of the IT infrastructure thanks to the hardware layer virtualization not only in terms of the calculation power but also the computer network of disk space. However, the structure simplification increases the scalability of the solution.

VSAN

vSAN is a VMWare solution for the hyper-convergence infrastructure deployment. The platform consists of the elements enabling the software definition of the calculation, network, and data media layer. The virtualization devices are most often booted on one physical machine equipped with adequate disk space. Such created resource can be a part of the cluster while the remaining nodes can use both the calculation power and the disk space.

The elements of one virtual machine such as the VMDK files, setting files, swap, etc. are called objects in terms of vSAN. The objects can be duplicated and spread over the cluster nodes. The data duplication policy deployment in the area of objects protects the virtual machines against failure in case of the unavailability of one of the virtual machine hosting subsystems irregardless of the fact if it is disk space, network or the calculation layer. Juggling the duplication and node spread parameters we can build an equivalent of the classic RAID systems on the level of the vSAN objects.

VSAN double-node cluster

The most commonly found vSAN VMWare solution deployment is the double-node cluster deployment. It is a relatively cheap solution because we do not use a dedicated data array to store the virtual machine images. The whole cluster can consist of two servers equipped with the adequate amount of disk space. Because the cluster has only two nodes the vMotion network and vSAN can be implemented directly in the server network interfaces without the intermediary switches. In case of the vSAN solution deployment based only on two nodes it is required to install a host called the witness. The witness host together with one server in case of the second node failure create kkforum and control the further cluster operation. vSAN Witness can be deployed also as virtual appliance but it cannot be hosted on the same environment that it controls. In practice the double-node clusters are most commonly used in the company branches while the witness can be installed in the company's headquarters.

Server deployment and administration

Our company provides IT services including the deployment and administration of the virtual solutions based on the vmWare and Microsoft Server. We also provide the services of the physicalserver and cluster administration. We prepare and perform the data migration from the physical environments to the clusters and the Microsoft Azure calculation cloud.