What Is VMware vSphere? A Deep Dive into Its Core Components and Storage Solutions

What Is VMware vSphere?

vSphere is VMware's next‑generation, cloud‑oriented data‑center virtualization suite that provides a complete solution for virtualized infrastructure, high availability, centralized management, and monitoring.

Main Components

ESXi

The virtualization layer for physical servers, abstracting CPU, memory, storage, and other resources into multiple virtual resources that are allocated to VMs via the vCenter management platform. ESX was deprecated in vSphere 5.0 due to security concerns.

vCenter

Provides centralized management of ESXi hosts and their VMs. It enables advanced features such as HA, DRS, vMotion, Storage vMotion, and distributed switches. vCenter can be extended with plugins (e.g., VMware Plug‑in) for additional capabilities and must run on a 64‑bit OS from version 4.1 onward.

vSphere Client

The management client that can connect directly to an ESXi host for basic tasks or to vCenter for centralized management of hosts and VMs.

vSphere Web Access

A web‑based interface allowing browser‑based management of vSphere or vCenter.

Disaster Recovery

SRM (Site Recovery Manager)

Provides vSphere Replication (optional host‑based replication), automated failback, and planned migration. Typical storage‑based replication solutions are also supported.

Backup Solutions

VADP (vStorage APIs for Data Protection)

Evolution of the older VCB (VMware Consolidated Backup) command‑line tools. VADP offers agent‑less, hot (online) backup, incremental and synthetic backups, consistency handling, file‑level restore, and instant recovery. It integrates with Windows VSS for application‑consistent snapshots of SQL Server, Exchange, etc. Major backup products such as CommVault (CV), NetBackup (NBU), Veeam, and vRanger support VADP.

VMware Consolidated Backup

A backup tool that requires both ESX and a Backup Proxy connected to shared SAN storage. It creates snapshots of running VMs after pausing applications, then a Windows backup proxy processes the snapshots for tape or disk backup, providing file‑level visibility and ensuring filesystem consistency.

Data Recovery (Virtual Machine Backup and Restore)

Provides snapshot‑based, deduplication‑enabled, agent‑less backup and restore at both VM and file levels, managed centrally through vCenter.

vStorage APIs

VAAI (vStorage APIs for Array Integration)

Introduced in vSphere 4.1 to offload certain operations from ESXi hosts to storage arrays, reducing host CPU load and improving performance. Features include:

Block zeroing – creating thick‑provisioned VMDK files directly on storage.

Full copy – delegating file copy operations (e.g., VM cloning, Storage vMotion) to the array.

Hardware‑assisted locking (ATS) – providing VMFS lock granularity.

Thin provisioning – supporting UNMAP space reclamation (added in vSphere 5.0, enhanced in 5.5).

VASA (vStorage APIs for Storage Awareness)

Introduced in vSphere 5.0 to integrate storage arrays with vCenter, exposing LUN information, health status, configuration, and capacity details.

VADP (re‑mentioned)

Offers agent‑less, hot backup, incremental, synthetic, consistency handling, file‑level restore, and instant recovery capabilities.

Storage Provisioning Methods

VMware storage is organized in three layers: VMDK (virtual disk format), VMFS (virtual machine file system), and the underlying hardware storage.

vSAN

A distributed storage component of vSphere that uses a distributed RAID/Rain approach instead of traditional RAID. The number of replica copies for a virtual disk depends on the VM storage policy; up to three copies can be placed on a 32‑node VSAN cluster.

VMFS

VMware's clustered file system, analogous to Windows NTFS or Linux ext2/ext3, enabling shared storage across multiple hosts. Many storage vendors build active‑active solutions on top of VMFS clustering.

RDM (Raw Device Mapping)

Maps a physical LUN directly to a specific VM, supporting iSCSI and Fibre Channel. In FC environments, HBA cards and switches must support NPIV (N‑Port ID Virtualization) to allow multiple virtual ports per physical port.

NFS/CIFS and vVol

External storage accessed via NFS or CIFS, with most modern arrays supporting vVols (requires VASA integration). vVol replaces traditional LUN‑based datastores with storage containers that expose per‑VM capabilities such as replication, deduplication, and snapshots.

vVol, introduced in vSphere 6, abstracts storage as virtual data stores regardless of underlying DAS, VSAN, or SAN/NAS, allowing storage policies to be applied at the individual VM level rather than at the LUN level.