Before delving into the installation and configuration of vSAN, it’s necessary to discuss the requirements and the prerequisites. VMware vSphere is the foundation of every vSAN based virtual infrastructure.

VMware vSphere:
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vSAN was first released with VMware vSphere 5.5 U1. Additional versions of vSAN were released with VMware vSphere 6.0 (vSAN 6.0), VMware vSphere 6.0 U1 (vSAN 6.1), and VMware vSphere 6.0 U2 (vSAN 6.2). Each of these releases included additional vSAN features.

VMware vSphere consists of two major components: the vCenter Server management tool and the ESXi hypervisor. To install and configure vSAN, both vCenter Server and ESXi are required.
VMware vCenter Server provides a centralized management platform for VMware vSphere environments. It is the solution used to provision new virtual machines (VMs), configure hosts, and perform many other operational tasks associated with managing a virtualized infrastructure.
To run a fully supported vSAN environment, the vCenter server 5.5 U1 platform is the minimum requirement, although VMware strongly recommends using the latest version of vSphere where possible. vSAN can be managed by both the Windows version of vCenter server and the vCenter Server appliance (VCSA). vSAN is configured and monitored via the vSphere web client, and this also needs a minimum version of 5.5 U1 for support. vSAN can also be fully configured and managed through the command-line interface (CLI) and the vSphere application programming interface (API) for those wanting to automate some (or all) of the aspects of vSAN configuration, monitoring, or management. Although a single cluster can contain only one vSAN datastore, a vCenter server can manage multiple vSAN and compute clusters.

ESXi:
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VMware ESXi is an enterprise-grade virtualization product that allows you to run multiple instances of an operating system in a fully isolated fashion on a single server. It is a baremetal solution, meaning that it does not require a guest-OS and has an extremely thin footprint. ESXi is the foundation for the large majority of virtualized environments worldwide. For standard datacenter deployments, vSAN requires a minimum of three ESXi hosts (where
each host has local storage and is contributing this storage to the vSAN datastore) to form a supported vSAN cluster. This is to allow the cluster to meet the minimum availability requirements of tolerating at least one host failure.

With vSAN 6.1 (released with vSphere 6.0 U1), VMware introduced the concept of a 2-node vSAN cluster primarily for remote office/branch office deployments. There are some additional considerations around the use of a 2-node vSAN cluster, including the concept of a witness host. As of vSAN 6.0 a maximum of 64 ESXi hosts in a cluster is supported, a significant increase from the 32 hosts that were supported in the initial vSAN release that was part of vSphere
5.5, from here on referred to as vSAN 5.5. The ESXi hosts must be running version 6.0 at a minimum to support 64 hosts however. At a minimum, it is recommended that a host have at least 6 GB of memory. If you configure a host to contain the maximum number of disk groups, we recommend that the host be configured with a minimum of 32 GB of memory. vSAN does not consume all of this memory, but it is required for the maximum configuration. The vSAN host memory requirement is directly related to the number of physical disks in the host and the number of disk groups configured on the host.In all cases we recommend to go with more than 32 GB per host to ensure that your workloads, vSAN and the hypervisor have sufficient resources to ensure an optimal user experience. Below is the Diagram for Minimum host contributing storage :

Cache and Capacity Devices:
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With the release of vSAN 6.0, VMware introduced the new all-flash version of vSAN. vSAN was only available as a hybrid configuration with version 5.5. A hybrid configuration is where the cache tier is made up of flash-based devices and the capacity tier is made up of magnetic disks. In the all-flash version, both the cache tier and capacity tier are made up of flash devices. The flash devices of the cache and capacity tier are typically a different grade of flash device in terms of performance and endurance. This allows you, under certain circumstances, to create all-flash configurations at the cost of SAS-based magnetic disk configurations.

 

vSAN Requirements:
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Before enabling vSAN, it is highly recommended that the vSphere administrator validate that the environment meets all the prerequisites and requirements. To enhance resilience, this list also includes recommendations from an infrastructure perspective:
>>Minimum of three ESXi hosts for standard datacenter deployments. Minimum of two ESXi hosts and a witness host for the smallest deployment, for example, remote office/branch office.
>>Minimum of 6 GB memory per host to install ESXi.
>>VMware vCenter Server.
>>At least one device for the capacity tier. One hard disk for hosts contributing storage to vSAN datastore in a hybrid configuration; one flash device for hosts contributing storage to vSAN datastore in an all-flash configuration.
>>At least one flash device for the cache tier for hosts contributing storage to vSAN datastore, whether hybrid or all-flash.
>>One boot device to install ESXi.
>>At least one disk controller. Pass-through/JBOD mode capable disk controller preferred.
>>Dedicated network port for vSAN–VMkernel interface. 10 GbE preferred, but 1 GbE supported for smaller hybrid configurations. With 10 GbE, the adapter does not need to be dedicated to vSAN traffic, but can be shared with other traffic types, such as management traffic, vMotion traffic, etc.
>>L3 multicast is required on the vSAN network.

vSAN Ready Nodes:
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vSAN ready nodes are a great alternative to manually selecting components. Ready nodes would also be the preferred way of building a vSAN configuration. Various vendors have gone through the exercise for you and created configurations that are called vSAN ready nodes. These nodes consist of tested and certified hardware only and, in our opinion,provide an additional guarantee.

For more information please follow : https://www.vsan-essentials.com/