VMware ESXi and vSphere Cluster Management

Edit Virtual Machine Settings in VMware vSphere

Learn how to edit an existing VM in the vSphere Web Client, including CPU, memory, disks, network adapters, controllers, RDM storage, VM options, and validation.

Editing virtual machine (VM) settings lets you change the hardware and management behavior of an existing VM without creating, cloning, or deleting it. Common changes include increasing CPU or memory for a growing workload, adding storage, connecting the VM to another virtual network, or adding a supported virtual device.

A virtual machine is a software-defined computer executed by an ESXi host and managed through vSphere. The vSphere Web Client is the browser-based interface used to administer that VM. Its Edit Settings dialog contains two main areas: Virtual Hardware and VM Options.

Why edit VM settings?

VM settings are changed to match workload, capacity, connectivity, and device requirements. For example, an application may need more processing capacity, a file server may need another disk, or a service may need a second network connection.

• Compute demand: Increase the number of virtual CPUs (vCPUs) or assigned memory when an application requires more resources.
• Storage growth: Add a virtual hard disk or, where required by the storage design, an RDM disk.
• Connectivity: Add a virtual network adapter and connect it to the intended virtual network.
• Device requirements: Add a USB controller, SATA controller, or another supported virtual device.
• Management behavior: Change guest time synchronization or VMware Tools update-check behavior.

These are configuration changes to an existing VM. They are different from creating a new VM, cloning a VM, or deleting a VM.

Open Edit Settings in the vSphere Web Client

1. Sign in to the vSphere Web Client with an account that has permission to modify the VM.
2. Open the inventory and locate the target VM.
3. Carefully confirm the VM name, host or cluster context, and current power state. Selecting the wrong VM can cause an unintended outage or configuration change.
4. Open the VM's context menu and choose Edit Settings.
5. Use the settings dialog to review or modify Virtual Hardware and VM Options.

Before changing anything, record the current configuration if your operational procedures require a change record. Check the VM's power state because it determines which operations are available.

Virtual Hardware settings

Virtual hardware consists of the virtualized devices assigned to a VM, including processors, memory, disks, controllers, and network adapters. In Edit Settings, you can add, remove, or modify supported hardware.

CPU and memory

A vCPU is a virtual processor assigned to the VM. Increasing the vCPU count can help a workload that has additional parallel processing demand, but it also consumes capacity from the ESXi host or cluster.

Virtual memory is the RAM capacity assigned to the VM. Increase it only when the guest and its workload need more memory and the host or cluster has sufficient capacity. Excessive allocation can reduce available capacity for other VMs.

• Review the current CPU and memory values before changing them.
• Determine whether the change is supported while the VM is running.
• If required, shut down the guest cleanly and power off the VM before editing.
• After saving and starting the VM, confirm that the guest operating system recognizes the new resources.

Virtual network adapters

A virtual network adapter connects the VM to a vSphere virtual network. When adding one, select the intended network and review the adapter's connection settings.

1. Add a virtual Ethernet adapter.
2. Attach it to the intended virtual network.
3. Use an online addition only when the VM configuration, vSphere capabilities, and guest operating system support it.
4. Configure or enable the new interface in the guest, including addressing and any required network policy.
5. Test communication on the intended network.

Virtual hard disks

A virtual hard disk is a disk device presented to the guest for operating-system or application storage. When adding a disk, select appropriate storage and disk settings according to your datastore and workload design.

1. Add the virtual hard disk in Edit Settings.
2. Select the appropriate datastore or storage location and configure the required capacity.
3. Save the VM configuration.
4. If the disk was added online, rescan storage in the guest when necessary.
5. Initialize, partition, format, or mount the disk inside the guest operating system.
6. Confirm that the expected capacity is available to the workload.

USB and SATA controllers

USB and SATA controllers provide virtual connection points for supported devices. Add the controller only when the guest or application requires it, and verify guest support for the resulting device layout.

In supported environments, a USB controller or SATA controller may be added while the VM is powered on. Availability depends on the VM configuration, vSphere capabilities, and guest operating system support.

Raw Device Mapping disks

Raw Device Mapping (RDM) is a virtual disk configuration that maps a VM to a physical storage device or LUN. Use it only when the storage design and workload require RDM behavior.

1. Choose the option to add an RDM disk in the VM hardware configuration.
2. Select the appropriate mapped storage device according to the storage design.
3. Review the controller and disk placement before saving.
4. Confirm that the guest detects the disk and that the workload can access it.

VM Options

VM Options are VM-level settings separate from the virtual hardware list. They affect how the VM and guest are managed rather than adding a processor, disk, controller, or adapter.

Guest time synchronization

Guest time synchronization controls whether the guest operating-system clock is synchronized with the virtualization environment. Review this setting against the organization's time-management policy and the guest's own time service. Inconsistent time sources can cause clock corrections or authentication problems.

VMware Tools update-check behavior

VMware Tools is guest-side integration software that supports management functions and improved guest interaction. The update-check setting controls whether the VM checks for VMware Tools updates according to the configured behavior. Review this option before saving so it matches the organization's maintenance and change-control policy.

Option changes should be reviewed just as carefully as hardware changes. They can affect guest operation, timekeeping, integration, and management behavior even when no virtual device is added.

Power-state requirements and hot-add

Hot-add means adding supported virtual hardware while a VM remains powered on. Many configuration changes still require the VM to be powered off, meaning the guest is shut down and the VM is not executing on the ESXi host.

The word “sometimes” does not guarantee that an operation is available. Check the controls in Edit Settings and the compatibility of the VM and guest. If the requested change cannot be made online, plan a maintenance window, shut down the guest cleanly, power off the VM, make the change, and restart it.

Save and validate the changes

1. Review every changed hardware item and VM option.
2. Confirm that the selected VM and power-state plan are correct.
3. Choose the dialog action that applies or saves the configuration.
4. Verify that the new device or value appears in the VM summary or hardware list.
5. For a running VM, validate the change inside the guest operating system when applicable.
6. Check network connectivity, storage visibility, and CPU or memory recognition as relevant to the change.

Practical configuration examples

Increase compute capacity

1. Open the VM's Edit Settings dialog.
2. Adjust the assigned vCPU count and memory capacity.
3. Power off the VM first if the requested change is not supported online.
4. Apply the change, start the VM if necessary, and confirm that the guest recognizes the new resources.

Connect to an additional network

1. Add a virtual Ethernet adapter.
2. Attach it to the intended virtual network.
3. Use hot-add only when the environment and guest support it; otherwise shut down the VM.
4. Configure the new interface in the guest and verify communication.

Provide more storage

1. Add a virtual hard disk and select suitable storage.
2. Use online disk addition only when supported.
3. Rescan the guest, then initialize, partition, format, or mount the disk as required.
4. Verify disk visibility and available capacity.

Change VM management behavior

1. Open the VM Options area of Edit Settings.
2. Review guest time synchronization and VMware Tools update-check settings.
3. Save the values that match operational policy.
4. Confirm the resulting behavior through the guest or management workflow.

Operational safeguards

• Plan a maintenance window or shutdown when the desired change cannot be completed while the VM is powered on.
• Shut down the guest cleanly before powering off a production VM.
• Do not remove disks, adapters, or controllers that are in active use.
• Confirm that CPU and memory increases fit host or cluster capacity.
• Confirm that new disks fit datastore capacity and storage policy.
• Confirm that new adapters use the correct virtual network and comply with network policy.
• Review the complete configuration before saving rather than changing multiple unrelated devices without a plan.

Troubleshooting common problems

A setting cannot be edited while the VM is running

The operation may not support online changes, or the VM or guest may not support the applicable hot-add capability. Check the power-state requirement for the intended change. If necessary, schedule a shutdown, modify the setting while the VM is powered off, restart the VM, and validate the result.

A new network adapter has no connectivity

• Confirm that the adapter appears in Edit Settings and is connected to the correct virtual network.
• Verify that the guest detected and enabled the new interface.
• Check IP addressing, routes, firewall rules, and network policy.
• Test reachability after the guest configuration is complete.

A new disk is not usable in the guest

• Confirm that the disk appears in the VM hardware list.
• Rescan storage or inspect devices in the guest.
• Check whether the disk needs initialization, partitioning, formatting, or mounting.
• Review the disk attachment and controller placement if the device is still absent.

The expected CPU or memory increase is not visible

• Reopen Edit Settings and check that the new values were saved on the correct VM.
• Determine whether the VM needed to be powered off and restarted.
• Refresh the guest hardware view or inspect its resource information.
• Confirm resource recognition in both vSphere and the guest.

Exam-relevant notes

• Edit Settings modifies an existing VM; it does not clone, create, or delete the VM.
• Hot-add is conditional, not universal. VM configuration, vSphere capabilities, and guest operating-system support all matter.
• USB controllers, SATA controllers, Ethernet adapters, and hard disks are examples of hardware that may be added online when supported.
• Many CPU, memory, removal, and other hardware operations require the VM to be powered off.
• A virtual network adapter provides connectivity through a vSphere virtual network; adding the adapter does not automatically complete guest IP configuration.
• Adding a virtual disk does not automatically initialize, format, or mount it inside the guest.
• VM Options, such as guest time synchronization and VMware Tools update checks, are separate from Virtual Hardware.

Configuration checklist

1. Confirm the selected VM name and current power state.
2. Choose the relevant hardware or VM Options category.
3. Add, remove, or modify the required setting.
4. Review whether shutdown is required.
5. Apply and save the changes.
6. Validate the result in vSphere and, where relevant, in the guest operating system.