VMware vSphere Glossary of Terms

In this post, I want to explain the most recent terms of VMware vSphere in short. Some of the features can be confusing and easily misunderstood, so I decided to create a brief identification of all these useful terms and features.

VM (Virtual Machine): A software-defined computer system that operates like a physical computer.

Guest OS (Operating System): The operating system running inside the VM, such as Linux, Windows, or other OS types. It should not be confused with the VM itself.

VMX: A file containing the VM configuration, including settings like memory allocation, BIOS type, and network adapter type.

VMDK (Virtual Machine Disk): A file representing the virtual disk of a VM, where the OS and data within the VM are stored.

VM Template: A copy of a VM’s disk file and configuration that cannot be used as a VM. It serves as a master copy for deploying new VMs.

OVF Template (Open Virtualization Format): A template used for deploying VMs to VMware and other virtualization platforms, consisting of multiple files.

OVA Template (Open Virtualization Appliance): Similar to an OVF template but packaged into a single file for easier distribution and deployment.

VM Snapshot: A technique to save a VM’s state at a specific point in time. It is not a full copy or backup of the VM.

VMware Tools: A set of utilities installed in the guest OS to improve management and performance, enabling features like graceful shutdowns from the host.

VM Compatibility Version: The version of the VM that corresponds to the version of vSphere. Each vSphere version has its own VM version.

Host (ESXi Host): A Type 1 hypervisor installed on a physical server to host VMs.

Server: The physical hardware on which ESXi is installed.

VMkernel: The core component of ESXi that provides virtualization functionality.

VMFS Datastore: A storage volume created by VMware to store VMs, templates, and other necessary files.

Storage Device: A LUN (Logical Unit Number) used to create a datastore. It should not be confused with the datastore itself.

Storage Adapter: An adapter that provides connectivity to storage devices, such as hardware iSCSI, software iSCSI, or Fiber Channel adapters.

Attach and Detach: Terms describing the online (attached) or offline (detached) status of storage devices on a host.

Mount and Unmount: Terms describing whether a datastore is accessible with a logical address (mounted) or not (unmounted).

vSAN: A software-defined shared storage solution by VMware that uses the local disks of servers to create an object-based storage system.

Storage Cluster: A cluster of multiple datastores that provides load balancing based on IOPS and capacity.

Storage DRS (Distributed Resource Scheduler): A feature of storage clusters that balances storage resources based on IOPS and capacity.

VMnic: The physical network adapter of a host. It should not be confused with virtual network adapters.

Virtual Machine Network Adapter: Virtual network devices within a VM, allowing network connectivity.

VMkernel Adapter: A virtual network adapter used for host connectivity, such as connecting to an iSCSI target server.

Virtual Switch: A software-defined network switch that connects virtual objects like VMs and VMkernel adapters to the physical network.

VSS (Virtual Standard Switch): A standalone virtual switch configured and running on a single host.

VDS (Virtual Distributed Switch): A distributed virtual switch configured on vCenter Server and running across multiple hosts.

Network Port Group: A segment within a virtual switch with its own configurations and VLANs.

vApp: A container for VMs that allows you to manage and configure them as a single unit, often used for multi-tier applications.

Resource Pool: A pool of compute resources (CPU and memory) allocated to multiple VMs, allowing for resource reservation and limitation.

Cluster: A group of hosts that form a unified virtualization resource with features like HA, DRS, and FT.

HA (High Availability): A cluster feature that restarts VMs on other hosts in the event of a failure.

DRS (Distributed Resource Scheduler): A cluster feature that balances VM workloads across hosts based on CPU and memory usage.

DPM (Distributed Power Management): A cluster feature that balances power consumption by powering down hosts when not needed. It depends on DRS.

Proactive HA: A cluster feature that works with DRS to evacuate VMs from a degraded host before a failure occurs.

FT (Fault Tolerance): A cluster feature that creates a secondary live copy of a VM, ensuring continuous availability if the primary VM fails.

Datacenter: A logical container in vSphere for organizing clusters, networking, and storage resources.

vSphere Client: The web management interface for the vSphere environment.

vSphere Host Client: The web management interface for individual ESXi hosts.

VAMI (vCenter Appliance Management Interface): The web interface for managing the vCenter Server Appliance itself.

VCSA (vCenter Server Appliance): The appliance used to install vCenter Server.

Photon OS: A Linux-based operating system developed by VMware, used for running VMware appliances.

VCHA (vCenter High Availability): A feature that creates a secondary vCenter VM and a witness node to ensure high availability of vCenter Server.

vSphere Lifecycle Manager: A tool for updating and patching vSphere objects, such as ESXi hosts, using a single image or baseline.

Host Profile: A feature for managing configurations across multiple hosts, allowing for the application of consistent settings.

Tanzu Kubernetes Grid: A VMware solution for running Kubernetes clusters on vSphere, enabling modern application development and management.

Content Library: A centralized repository for VM templates, ISO images, and other files that can be shared across the vSphere environment.

Workload Management: A feature that integrates Kubernetes into vSphere, allowing for the deployment and management of containerized applications.

Namespaces: Logical entities within vSphere with Kubernetes, used to organize and manage resources for different teams or projects.

Hybrid Cloud Service: VMware’s approach to integrating on-premises vSphere environments with public cloud services for greater flexibility and scalability.

Auto Deploy: A feature that allows for the automated deployment and provisioning of ESXi hosts over the network, simplifying large-scale host management.

---

This glossary provides a clear and concise explanation of each term, helping to avoid confusion and ensure understanding of VMware vSphere features and concepts. If you have any other terms you’d like to define, let me know, and I will update this post.