VMware ESXi and vSphere Cluster Management
What Is a Datastore in VMware ESXi and vSphere?
Learn what VMware vSphere datastores are, what they store, how VMFS and NFS differ, where storage resides, and how to browse datastores in the vSphere Client.
What Is a VMware Datastore?
A datastore is a logical storage container that VMware vSphere uses to store virtual machine and related files. ESXi is the bare-metal hypervisor that runs virtual machines and accesses these datastores. vSphere is VMware's virtualization platform and management ecosystem.
The datastore gives administrators and ESXi hosts a consistent way to work with virtual infrastructure files. The same logical view can be used whether the storage underneath is an internal disk, a storage-area network (SAN), or a network-attached storage (NAS) system.
Datastore and physical storage compared
- Physical storage: The disks, storage array, LUN, or file share that provides capacity.
- Protocol or presentation: The method ESXi uses to access that capacity, such as block storage or NFS.
- Datastore: The logical vSphere object where VM files and other virtual infrastructure files are organized.
What Does a Datastore Store?
Datastores hold the files that make up virtual machines and support their operation. They also commonly provide a central location for deployment media and reusable VM images.
| File or content type | Purpose | Administrative caution |
|---|---|---|
| Virtual disks | Files, commonly using the VMDK extension, that contain a VM's guest operating system, applications, and data. | Do not delete or move a virtual disk while a VM depends on it. |
| VM configuration files | Describe the VM's virtual hardware and configuration. A configuration file commonly uses the VMX extension. | Changing or removing configuration files can prevent the VM from powering on or being registered correctly. |
| Snapshot-related files | Store changes made after a VM snapshot is created. | Snapshots can consume substantial space. Manage them through supported VM workflows. |
| Log files | Record VM events and can help with troubleshooting. | Old logs may be removable according to operational policy, but confirm they are no longer needed. |
| Swap files | Provide VM memory swap space when required by the host configuration. | They may appear or disappear as VM power state and configuration change. |
| Templates | Reusable master images used to deploy new virtual machines. | Protect templates from accidental modification or deletion. |
| ISO images | Optical-disc image files used to install guest operating systems or applications. | Remove only confirmed-unused images because installations or recovery tasks may depend on them. |
Centralized datastore storage simplifies VM deployment, cloning, template use, ISO management, backup integration, and file administration. On shared storage, multiple eligible ESXi hosts can access the same VM files, which is important for operations such as migrations and clustered availability features.
Centralization does not remove the need for planning. Capacity, performance, host connectivity, redundancy, permissions, and storage protocol behavior all affect how suitable a datastore is for a workload.
Where Can a Datastore Reside?
Local datastore
A local datastore is backed by disks installed in an ESXi server. For example, an administrator can create a VMFS datastore on internal disks and store VMs that run on that host.
Local storage can be useful for standalone hosts or workloads that do not require shared access. Because the disks are inside one server, another ESXi host generally cannot access the datastore unless the workload and storage are moved or copied elsewhere.
Shared SAN storage
A SAN, or storage-area network, commonly provides shared block storage to servers. The storage system presents a LUN, which is a logical unit of block storage, to one or more ESXi hosts.
ESXi can format an appropriately presented shared LUN with VMFS. When the hosts have the required storage connectivity and configuration, they can mount the same VMFS datastore and access eligible VM files.
NAS and NFS storage
NAS, or network-attached storage, provides file-based storage over a network. A NAS system can export a directory using NFS. ESXi mounts that export as an NFS datastore.
With an NFS datastore, ESXi does not format the exported storage with VMFS. The NAS system retains and manages its own native file system, while ESXi uses the NFS export as its datastore interface.
| Datastore type | Backing storage | Typical access method | Who manages the file system | Common use |
|---|---|---|---|---|
| Local VMFS datastore | Disks installed in an ESXi server | Local block-device access | VMware VMFS on the ESXi-accessible device | Standalone or host-local workloads |
| Shared SAN VMFS datastore | Shared storage-array LUN | SAN block protocols such as Fibre Channel or iSCSI | VMware VMFS, with the storage array providing the block device | VMs that require shared access by multiple ESXi hosts |
| NFS datastore | Directory exported by a NAS system | NFS over the storage network | The NAS provider's native file system | File-based shared storage and centralized VM files |
The datastore interface hides many hardware and protocol differences. However, those differences still affect performance, availability, sharing capabilities, backup design, and operational procedures. Protocol selection is therefore a storage architecture decision, not merely a naming choice.
VMFS and NFS Datastores
VMFS
VMFS means Virtual Machine File System. It is VMware's clustered file system for block-storage datastores. A VMFS datastore is created on a block device, such as a local disk or a SAN LUN.
VMFS is designed for coordinated access by multiple ESXi hosts when the underlying block storage is shared and correctly configured. This allows hosts to recognize and work with the same datastore without treating each host's access as an unrelated file system.
VMFS5 is a VMFS format version that may appear in older or existing environments. The version affects capabilities and compatibility, so identify the version before planning storage changes or migrations.
NFS
An NFS datastore is created by mounting an NFS export from a NAS system. The NAS owns the underlying file system and presents a network share; ESXi consumes that share as a datastore.
VMFS and NFS are different datastore implementations. VMFS is used with block storage that ESXi formats and mounts, whereas NFS uses a file share whose file system remains on the NAS. They are not interchangeable formatting options for the same storage presentation.
For related configuration procedures, see Create a VMFS Datastore and Configure an NFS Datastore.
Viewing Datastores in the vSphere Client
vCenter Server is the centralized vSphere management platform used to manage inventory objects such as ESXi hosts, virtual machines, clusters, and datastores.
- Sign in to the vSphere Client through vCenter Server.
- Open the vCenter inventory.
- Select Datastores to display the datastore inventory view.
- Review the datastore list and select a datastore for more information.
The exact placement of inventory controls can vary slightly between vSphere versions and client layouts, but the Datastores inventory object is the starting point for viewing datastore resources.
A datastore list typically shows information such as:
- Datastore name
- Datastore type, such as VMFS or NFS
- Total capacity
- Free or available space
- Accessible or connected ESXi hosts
An environment can contain many datastores. Each datastore has its own capacity, free-space level, type, backing storage, and host-access configuration. Similar names do not mean that two datastore objects share capacity or accessibility.
Viewing Datastore Details
Selecting or opening a datastore displays details about its configuration, usage, and relationships to other vSphere objects. The available panels depend on the vSphere version and the user's permissions.
Useful details to inspect include:
- Datastore type: Identifies whether the datastore uses VMFS, NFS, or another supported implementation.
- Capacity and free space: Shows whether the datastore can safely accept additional VM files or growth.
- Backing device or NFS source: Identifies the underlying block device, LUN, or NFS export.
- Connected hosts: Shows which ESXi hosts can access the datastore.
- Related virtual machines: Shows workloads using the datastore.
Check these details before placing a new VM, changing a VM's storage location, or migrating a workload. A datastore may have sufficient free space but still be unsuitable if the destination host cannot access it or if its performance and availability characteristics do not meet the workload's needs.
Browsing and Managing Datastore Files
The datastore browser is the vSphere interface for viewing datastore folders and performing selected file operations.
- Open the Datastores inventory view.
- Select the target datastore.
- Open the datastore actions or context menu, or use the datastore details page.
- Choose Browse Files or the equivalent datastore-browser command.
- Select a folder to inspect its contents and use supported actions as needed.
Common basic operations include browsing folders, uploading files, moving files where supported, and deleting files. A typical safe use is uploading an ISO image to a clearly named location, then selecting that ISO as the virtual CD/DVD media for a VM.
| Task | Where to perform it | Outcome | Caution |
|---|---|---|---|
| View datastore inventory | vCenter inventory > Datastores | Lists datastore names, types, capacity, free space, and host access. | Confirm that you are viewing the intended vCenter environment. |
| Open datastore details | Select a datastore in the inventory | Shows configuration, backing storage, usage, hosts, and related VMs. | Check host accessibility before using the datastore as a destination. |
| Browse files | Datastore actions or context menu > Browse Files | Displays folders and files in the datastore. | Do not change VM files without understanding their role. |
| Upload an ISO | Datastore browser upload action | Places installation media on the datastore for VM access. | Verify sufficient space and host access to the datastore. |
| Move or delete a file | Datastore browser file actions | Changes datastore contents. | Confirm the file is unused and safe to change; prefer supported VM workflows. |
For a focused walkthrough of file browsing, see Browse VMFS Datastores. To use an uploaded image during deployment, see Install a Guest Operating System.
Storage Protocol Context
| Storage context | How ESXi accesses it | Sharing characteristic | Design considerations |
|---|---|---|---|
| Local storage | Through disks installed in the ESXi host | Usually limited to that host | Simple topology, but limited shared access and host-level redundancy. |
| SAN or block storage | Through a presented LUN over a storage network, then commonly VMFS | Can be shared by multiple ESXi hosts when correctly configured | Requires storage-network connectivity, multipathing or equivalent design, and careful LUN presentation. |
| NAS or NFS storage | By mounting an NFS export from a NAS system | Designed for network-based shared file access | Depends on NAS availability, NFS network performance, export permissions, and correct host access. |
The selected protocol influences performance, availability, sharing capabilities, and day-to-day operations. A datastore's name alone does not describe all of these characteristics; inspect its type, backing, and accessible hosts in vSphere.
Practical Datastore Examples
Local ESXi storage
An ESXi host has internal disks. An administrator creates a VMFS datastore on those disks and stores virtual machines there. Those VMs normally run only on that host unless their files are copied or migrated to storage accessible by another host.
Shared SAN storage
Several ESXi hosts access the same SAN LUN. The LUN is formatted as VMFS and appears as a shared datastore. Eligible hosts can access VM files stored there, subject to their connectivity and vSphere configuration.
NFS-based storage
A NAS appliance exports an NFS share. ESXi mounts the share as an NFS datastore, while the NAS continues to manage its native file system.
ISO library
An administrator uploads a guest operating system ISO to a datastore, then attaches it to a new VM's virtual CD/DVD drive during installation. The VM's host must be able to access the datastore and the ISO path selected in the VM settings.
Troubleshooting Datastore Problems
A datastore does not appear for an ESXi host
Possible causes include missing connectivity to the SAN, NAS, or local device; a storage device or LUN that has not been presented; an unreachable or unauthorized NFS export; or a mount or storage-rescan requirement.
- Verify the host's connectivity to the relevant storage network.
- Confirm that the datastore is intended to be accessible by that host.
- Check datastore and host visibility in vSphere before changing storage configuration.
- For block storage, verify that the expected device or LUN is presented to the host.
- For NFS, verify export reachability and authorization for the host.
A datastore has insufficient free space
VM virtual disks, snapshots, logs, ISO files, and unused content can consume capacity. Multiple workloads may also have been placed on the datastore without sufficient growth planning.
- Review the datastore's capacity and free-space details.
- Use the datastore browser to identify confirmed-unused ISO images or other content.
- Review VM disk growth and snapshots before removing anything.
- Do not delete VM-related files merely because their names are unfamiliar.
A VM fails after files were moved or deleted
A required configuration file, virtual disk, snapshot component, or other dependency may have been changed outside normal VM management workflows.
- Stop making additional file changes.
- Determine which files belong to the affected VM.
- Check whether a valid backup or known-good copy exists.
- Use supported VM and datastore management workflows instead of manually manipulating unknown files.
An uploaded ISO cannot be used
- Confirm the ISO's location in the datastore browser.
- Verify that the VM's current host can access that datastore.
- Review the VM's virtual CD/DVD device and select the intended ISO path.
- Confirm that the virtual device is connected when the VM starts or during the installation.
Exam-Relevant Notes
- A datastore is a logical vSphere storage container, not a physical disk or storage array.
- VMFS is VMware's clustered file system for block-storage datastores.
- A shared VMFS datastore can be mounted by multiple ESXi hosts when shared storage is correctly presented and configured.
- An NFS datastore mounts a NAS export; the NAS retains and manages its native file system.
- A SAN commonly presents block storage as LUNs, while NAS commonly provides file-based NFS shares.
- The datastore browser can perform useful file tasks, but direct changes to VM files can make a VM unavailable or damage its dependencies.
To continue with the broader storage model, review Datastore in Virtual SAN and related datastore creation and expansion procedures.