What is VMware vSAN

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An Overview Of VMware vSAN

VMware vSAN is a software-defined, enterprise storage solution that supports hyper-converged infrastructure (HCI) systems. vSAN is fully integrated with VMware vSphere, as a distributed layer of software within the ESXi hypervisor. It means you do not need to install any external plugin to use VMware vSAN services in the vSphere.

VMware vSAN aggregates local or direct-attached data storage devices, to create a single storage pool shared across all hosts in a vSAN cluster.

Also, VMware vSAN eliminates the need for external shared storage and simplifies storage configuration through Storage Policy-Based Management (SPBM). Using a virtual machine (VM) storage policies, you can define storage requirements and capabilities.

It means VMware vSAN does not use iSCSI, NFS, or any kind of external storage adapter to communicate with virtual machines and storage systems.

VMware vSAN Current Version

The latest version of VMware vSAN 7.0 which is well compatible with ESXi 7.0. To know more about Build numbers and versions of VMware vSAN visit the KB Article 2150753.

Why Choose VMware vSAN for Hyperconverged Infrastructure(HCI)?

  • Integrated with Your Hypervisor – Enjoy scalable, high-performance, and secure infrastructure with the only vSphere-integrated storage virtualization software.
  • Lower Costs – Achieve a better price per performance by supporting the latest storage technology on industry-standard servers.
  • Private Cloud and Hybrid Cloud Ready – Use HCI anywhere with the industry’s broadest ecosystem: 18 OEM server vendors and native services with leading public clouds including AWS, Azure, Google Cloud, Oracle Cloud, IBM Cloud, and Alibaba Cloud.
  • Cloud-Native Applications – Both virtual machine and container applications could be managed seamlessly, and benefit from integration with leading container orchestrators such as Kubernetes.
  • Simplified Operations – Easily roll out new infrastructure and applications with minimal training.

VMware vSAN Configuration Types

There are two types of VMware vSAN configuration approach:

  1. Hybrid vSAN Cluster
  2. All-Flash vSAN Cluster

A hybrid vSAN cluster uses flash devices for the cache tier and magnetic drives for the capacity tier. An all-flash vSAN cluster uses flash devices for both the cache tier and the capacity tier. This architecture creates a flash-optimized, resilient shared datastore designed for the software-defined data center (SDDC). It plays an important role in SDDC for virtualized storage systems.

Let’s have a look on VMware vSAN 6.7 architectural overview.

VMware vSAN 6.7

VMware vSAN 6.7 delivers a new HCI experience with enhanced operational efficiencies that reduces time-to-expertise and accelerates decision-making.

This release provides a more consistent, resilient, and secure application experience, and leverages people, technology and analytics to deliver an enhanced support experience with a simpler, faster time to resolution.

Characteristics of VMware vSAN

There are many important characteristics of VMware vSAN. Few are below:

  • Shared Storage Support: It has the support of VMware features such as HA, vMotion, and DRS.
  • On-disk Format: vSAN 6.x supports on-disk virtual file format 5.0, which provides highly scalable snapshot and clone management support per vSAN cluster.
  • All-flash and hybrid configurations: vSAN can be configured for all-flash or hybrid clusters.
  • Fault Domains: It supports configuring fault domains to protect hosts from rack or chassis failures when the vSAN cluster spans across multiple racks or blade server chassis in a data center.
  • Stretched Cluster: vSAN 6.7 supports stretched clusters that span across two geographic locations.
  • vSAN Health Service Dashboard: vSAN health service includes preconfigured health check tests to monitor, troubleshoot, diagnose the cause of cluster component problems, and identify any potential risk.
  • VM Storage Policies: vSAN 6.7 works with VM storage policies to support a VM-centric approach to storage management. If no storage policy applied, the default storage policy will be applied.
  • Fast Provisioning: It speeds up in new provisioning of resources.

What is new in VMware vSAN 6.7

There are always new features coming in the newly released version of vSAN. Let’s have a look at some major improvements in vSAN 6.7:

  • New HTML5 User Interface
  • Introduced vRealize Operations within Center Server
  • Introducing vSAN ReadyCare
  • FIPS 140-2 Validated Encryption
  • Increased Application Resiliency
  • Enhanced Stretched Cluster Availability
  • Increased Support for Business-Critical Application Deployments
  • Proactive Support via vSAN Support Insight with VMware support
  • Adaptive Core Dump Support
  • Increased Hardware Support

Basic Terminology of VMware vSAN | Virtual SAN

Disk Group

The devices on the contributing host form one or more disk groups. Each disk group contains one flash cache device, and one or multiple capacity devices for persistent storage.

Each host can be configured to use multiple disk groups. And disk group could be five for a host having a maximum of seven storage devices attached to it. Out of seven one disk will be used as Flash and the other six will be used as a capacity disk.

The devices used for caching cannot be shared across disk groups, and can not be used for other purposes.

Consumed Capacity

Consumed capacity is the amount of physical capacity consumed by one or more virtual machines at any point.

Object-Based Storage

vSAN stores and manages data in the form of flexible data containers called objects. An object is a logical volume that has its data and metadata distributed across the cluster.

vSAN Datastore

vSAN datastore is an important part of the whole setup. It is created automatically when enabled vsan.

Component Of VMware vSAN

A vSAN datastore contains the many object types such as VM Home Namespace, VMDK, VM Swap Object, and Snapshot Delta VMDKs.

VM Home Namespace

This is the virtual machine home directory where all virtual machine configuration files are stored, such as .vmx, log files, vmdk files, and snapshot delta description files.


A virtual machine disk or .vmdk file that stores the contents of the virtual machine’s hard disk drive.

VM Swap Object

Created when a virtual machine is powered on.

Snapshot Delta VMDKs

Created when virtual machine snapshots are taken.

VMware vSAN Objects Status

Virtual Machine Compliance Status: Compliant or Noncompliant

A virtual machine is considered noncompliant when one or more of its objects fail to meet the requirements of its assigned storage policy. For example, the status might become noncompliant when one of the mirror copies is inaccessible.

If your virtual machines are in compliance with the requirements defined in the storage policy, the status of your virtual machines is compliant.

Component State: Degraded and Absent States

vSAN acknowledges the following failure states for components.

  • Degraded state: A component is Degraded state when vSAN detects a permanent component failure and determines that the failed component cannot recover to its original working state.
  • Absent state: A component is Absent when vSAN detects a temporary component failure where components, including all its data, might recover and return vSAN to its original state.

Object State: Healthy and Unhealthy

  • Healthy: When at least one full RAID 1 mirror is available, or the minimum required the number of data segments is available, the object is considered healthy.
  • Unhealthy: An object is considered unhealthy when no full mirror is available or the minimum required a number of data segments are unavailable for RAID 5 or RAID 6 objects. If fewer than 50 percent of an object’s votes are available, the object is unhealthy. Multiple failures in the cluster can cause objects to become unhealthy.

VMware vSAN Witness

A witness is a component that contains only metadata and does not contain any actual application data. It serves as a tiebreaker when a decision must be made regarding the availability of the surviving datastore components, after a potential failure.

A witness consumes approximately 2 MB of space for metadata on the vSAN datastore when using on-disk format 1.0, and 4 MB for on-disk format for version 2.0 and later.

Storage Policy-Based Management (SPBM)

Storage Policy-Based Management(SPBM) is the main feature of vSAN. This makes a big difference than traditional storage model. When you enable vSAN in the virtual environment, it automatically assign storage policy automatically to manage the performance and availability of storage.

It ensures that the virtual machines deployed to vSAN datastores are assigned at least one virtual machine storage policy. If you want to apply a custom policy, you can also configure it to the virtual machine.

Ruby vSphere Console (RVC)

The Ruby vSphere Console (RVC) provides a command-line interface used for managing and troubleshooting the vSAN cluster. It gives you a cluster-wide view, instead of the host-centric view offered by esxcli. RVC is bundled with vCenter Server Appliance and vCenter Server for Windows, so you do not need to install it separately.

It is good for a programmer or one who does not want to login to vCenter all the time. vSAN Observer is a web-based tool powered by RVC to view, manage, and troubleshoot with vSAN cluster issues.

VMware vSphere PowerCLI

VMware vSphere PowerCLI adds command-line scripting support for vSAN, to help you automate configuration and management tasks. vSphere PowerCLI provides a Windows PowerShell interface to the vSphere API. PowerCLI includes cmdlets for administering vSAN components.

Deployment model for the VMware vSAN Cluster

There are two deployment models available with VMware vSAN:

  1. vSAN Ready Node

This is a preconfigured solution of the vSAN software provided by VMware partners networks such as Rackspace, IBM, and Cisco. This solution highly tested and would be a robust solution for someone who just doesn’t want to configure vSAN from scratch.

2. User-Defined vSAN Cluster

You can build a vSAN cluster by selecting individual software and hardware components, such as drivers, firmware, and storage I/O controllers that are listed in the vSAN Compatibility Guide. For host inside the vSAN cluster must be at similar software, firmware, and configuration otherwise you may encounter huge problems in your operations.

Limitations of VMware vSAN

While working with vSAN, you must consider the following Limitations of VMware vSAN:

  • vSAN does not support hosts participating in multiple vSAN clusters. However, a vSAN host can access other external storage resources that are shared across clusters.
  • vSAN does not support vSphere DPM and Storage I/O Control.
  • vSAN does not support SE Sparse disks.
  • vSAN does not support RDM, VMFS, diagnostic partition, and other device access features.
  • vSAN is limited to the vSAN cluster only.

VMware Compatibility Guide For vSAN

Before starting to deploy the vSAN cluster you must check and validate on VMware compatibility guide for vSAN on the VMware site.

It will help you to understand following things regarding VMware vSAN:

To know more about VMware vSAN HCL, Please visit our blog on vSAN Health Alarm ‘VSAN HCL DB Up-To-Date’.

Hardware Requirements

Storage Device/Component Requirements


  • One SAS or SATA solid-state disk (SSD) or flash device.
  • These devices must not be formatted with VMFS or another file system.

Virtual Machine Data Storage

  • In hybrid group configuration, make sure that at least one SAS or NL-SAS magnetic disk is available.
  • In all-flash disk group configuration, make sure at least one SAS, or SATA solid-state disk (SSD), or flash device.

Storage Controllers

  • One SAS or SATA host bus adapter (HBA), or a RAID controller that is in passthrough mode or RAID 0 mode.

Cluster Requirements for vSAN

  • All capacity devices, drivers, and firmware versions in your vSAN configuration must be certified and verified from the VMware site.
  • A vSAN cluster must contain a minimum of three hosts that contribute capacity to the cluster.
  • A host that resides in a vSAN cluster must not participate in other clusters.

Software Requirements for vSAN

To use the full set of vSAN capabilities, the ESXi hosts that participate in vSAN clusters must be version 6.5 or later. Also, check the software and firmware version for all ESXi.

Networking Requirements for vSAN

You must verify the below minimum requirements for networking to enable the vSAN cluster:

  • Host Bandwidth: Each host must have minimum bandwidth dedicated to vSAN. For hybrid 1 GB of dedicated bandwidth and for all-flash 10 GB dedicated bandwidth.
  • The connection between hosts: Each host must configure a VMKernal network adapter for vSAN traffic.
  • IPv4 and IPv6 support: vSAN supports both.

VMware vSAN 6.7/7.0 Licensing Guide

In the vSAN 6.7/7.0 licensing guide , we will help to understand VMware vSAN 6.7/7.0 licensing system. First of all to configure vSAN, you must have the required license from VMware. You can assign a standard vSAN license to the cluster, or a license that covers advanced functions.

VMware vSAN license editions include Standard, Advanced, Enterprise, and Enterprise Plus. The following table shows the available features.

vSAN License Editions

For detailed information you may refer VMware vSAN License Guide.

VMware vSAN 6.7 Sizing, Setup, And Enablement

vSAN delivers flash-optimized, secure shared storage with the simplicity of a VMware vSphere-native experience for all your critical virtualized workloads. vSAN runs on industry-standard x86 servers and components that help lower TCO by up to 50% versus traditional storage.

To use vSAN, you must create a host cluster and enable vSAN on the cluster. A vSAN cluster can include hosts with capacity and hosts without capacity. See below needs:

  • A vSAN cluster must include a minimum of three ESXi hosts (two ESXi hosts, if you use the 2-node option with Witness Appliance).
  • All hosts in the vSAN cluster must have the same on-disk format.
  • To be able to access the vSAN Datastore, an ESXi host must be a member of the vSAN cluster.

Steps to enable VMware vSAN services

To use vSAN, you must create a host cluster and enable vSAN on the cluster. A vSAN cluster can include hosts with capacity and hosts without capacity.

Basic Requirements

  • A vSAN cluster must include a minimum of three ESXi hosts (two ESXi hosts, if you use the 2-node option with Witness Appliance).
  • For the cluster to tolerate host and device failures, at least three hosts that join the vSAN cluster must contribute capacity to it. For best results, consider adding four or more hosts contributing capacity to the cluster.
  • All hosts in the vSAN cluster must have the same on-disk format.
  • To be able to access the vSAN Datastore, an ESXi host must be a member of the vSAN cluster.

Let’s start

After you enable vSAN, the vSAN storage provider is automatically registered with vCenter Server and the vSAN Datastore is created.

As part of the basic configuration keep the default selection of Single site cluster.

Let’s start enabling the vSAN step by step. Here We are using VMware Hands-on Lab for the demonstration purpose. This is easily available for you.

  1. Configure vSAN: Cluster -> Configure -> vSAN -> Services -> Turned On
vSAN Configure
vSAN Configure

2. Configuration Type: Select the ‘Single Site Cluster’ option from configuration type

vSAN Configuration Type
vSAN Configuration Type

3. vSAN Services: Select the services to enable.

Enable Deduplication and Compression also enable Encryption. Select Allow Reduced Redundancy and Click Next.

4. vSAN Disks: You have to claim the disks. One for flash cache disk and the rest will be capacity disk per host.

vSAN Claim Disk
vSAN Claim Disk

5. vSAN Fault Domain: We will not create Fault Domains right now. By default, each ESXi host in itself is a Fault Domain.

vSAN Fault Domain
vSAN Fault Domain

6. Review and Finish the setup.

vSAN Review
vSAN Review

7. Visit the vSAN Service: Cluster -> Configure -> vSAN -> Services

vSAN Service
vSAN Service

8. vSAN Health: Cluster -> Configure -> vSAN -> Health

vSAN Health
vSAN Health

9. vSAN Virtual Objects: Cluster -> Configure -> vSAN -> Objects

vSAN Virtual Object
vSAN Virtual Object

10. Physical Placement of Objects: Cluster -> Configure -> vSAN -> Virtual Objects -> Select the VM/Hard disk -> Click Placement and Availability

vSAN Placement
vSAN Placement

11. Resyncing Objects: Cluster -> Configure -> vSAN -> Resyncing Objects
It displays the status of objects that are currently being resynchronized in the vSAN cluster.

vSAN Resyncing Object
vSAN Resyncing Object

12. vSAN Health Status: As you can see the one of the host is down in the cluster. vSAN is showing the same error of host disconnection.

vSAN Health Status
vSAN Health Status

13. vSAN Datastore: Here is the view of your vSAN datastore.

vSAN Datastore
vSAN Datastore

14. vSAN Physical Disk: Cluster -> Configure -> vSAN -> Capacity

vSAN Capacity
vSAN Capacity

Enabling vSAN creates a vSAN Datastore and registers the vSAN Storage Provider. vSAN Storage Providers are built-in software components that communicate the storage capabilities of the datastore to vCenter Server.

Note: All above images are taken from VMware Hands-on Lab Environment.

Live Optics

Live Optics is a tool widely adopted across the industry which is used to capture workload metrics which allows customers to assess their current environments.

The VMware HCI assessment will capture metrics required for sizing and designing an HCI solution and will allow you to translate data into the vSAN ReadyNode Sizer to build a custom vSAN solution.

This is a very basic introduction of VMware vSAN. There is a lot of things to cover on vSAN. We will see new things in our new blog post.


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