Mar 052023

In this NVIDIA vGPU Troubleshooting Guide, I’ll help show you how to troubleshoot vGPU issues on VMware platforms, including VMware Horizon and VMware Tanzu. This guide applies to the full vGPU platform, so it’s relevant for VDI, AI, ML, and Kubernetes workloads.

This guide will provide common troubleshooting methods, along with common issues and problems associated with NVIDIA vGPU as well as their fixes.

Please note, there are numerous other additional methods available to troubleshoot your NVIDIA vGPU deployment, including 3rd party tools. This is a general document provided as a means to get started learning how to troubleshoot vGPU.


NVIDIA vGPU is a technology platform that includes a product line of GPUs that provide virtualized GPUs (vGPU) for Virtualization environments. Using a vGPU, you can essentially “slice” up a physical GPU and distribute Virtual GPUs to a number of Virtual Machines and/or Kubernetes containers.

Picture of NVIDIA A2 vGPU installed in VMware ESXi Server
NVIDIA vGPU Installed in VMware ESXi Host

These virtual machines and containers can then use these vGPU’s to provide accelerated workloads including VDI (Virtual Desktop Infrastructure), AI (Artificial Intelligence), and ML (Machine Learning).

While the solution works beautifully, when deployed incorrectly or if the solution isn’t maintained, issues can occur requiring troubleshooting and remediation.

At the end of this blog post, you’ll find some additional (external) links and resources, which will assist further in troubleshooting.

Troubleshooting Index

Below, you’ll find a list of my most commonly used troubleshooting methods.

Please click on an item below which will take you directly to the section in this post.

Common Problems Index

Below is a list of problems and issues I commonly see customers experience or struggle with in their vGPU enabled VMware environments.

Please click on an item below which will take you directly to the section in this post.


Using “nvidia-smi”

The NVIDIA vGPU driver comes with a utility called the “NVIDIA System Management Interface”. This CLI program allows you to monitor, manage, and query your NVIDIA vGPU (including non-vGPU GPUs).

Screenshot of "nvidia-smi" command running on VMware ESXi host with NVIDIA GPU
NVIDIA vGPU “nvidia-smi” command

Simply running the command with no switches or flags, allow you to query and pull basic information on your vGPU, or multiple vGPUs.

For a list of available switches, you can run: “nvidia-smi -h”.

Running “nvidia-smi” on the ESXi Host

To use “nvidia-smi” on your VMware ESXi host, you’ll need to SSH in and/or enable console access.

When you launch “nvidia-smi” on the ESXi host, you’ll see information on the physical GPU, as well as the VM instances that are consuming a virtual GPU (vGPU). This usage will also provide information like fan speeds, temperatures, power usage and GPU utilization.

[[email protected]:~] nvidia-smi
Sat Mar  4 21:26:05 2023
| NVIDIA-SMI 525.85.07    Driver Version: 525.85.07    CUDA Version: N/A      |
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|                               |                      |               MIG M. |
|   0  NVIDIA A2           On   | 00000000:04:00.0 Off |                  Off |
|  0%   36C    P8     8W /  60W |   7808MiB / 16380MiB |      0%      Default |
|                               |                      |                  N/A |

| Processes:                                                                  |
|  GPU   GI   CI        PID   Type   Process name                  GPU Memory |
|        ID   ID                                                   Usage      |
|    0   N/A  N/A   2108966    C+G   VM-WS02                          3904MiB |
|    0   N/A  N/A   2108989    C+G   VM-WS01                          3904MiB |

This will aid with troubleshooting potential issues specific to the host or the VM. The following pieces of information are helpful:

  • Driver Version
  • GPU Fan and Temperature Information
  • Power Usage
  • GPU Utilization (GPU-Util)
  • ECC Information and Error Count
  • Virtual Machine VMs assigned a vGPU
  • vGPU Type (C+G means Compute and Graphics)

Additionally, instead of running once, you can issue “nvidia-smi -l x” replacing “x” with the number of seconds you’d like it to auto-loop and refresh.


nvidia-smi -l 3

The above would refresh and loop “nvidia-smi” every 3 seconds.

For vGPU specific information from the ESXi host, you can run:

nvidia-smi vgpu
[email protected]:~] nvidia-smi vgpu
Mon Mar  6 11:47:44 2023
| NVIDIA-SMI 525.85.07              Driver Version: 525.85.07                 |
| GPU  Name                       | Bus-Id                       | GPU-Util   |
|      vGPU ID     Name           | VM ID     VM Name            | vGPU-Util  |
|   0  NVIDIA A2                  | 00000000:04:00.0             |   0%       |
|      3251713382  NVIDIA A2-4Q   | 2321577  VMWS01              |      0%    |

This command shows information on the vGPU instances currently provisioned.

There are also a number of switches you can throw at this to get even more information on vGPU including scheduling, vGPU types, accounting, and more. Run the following command to view the switches:

nvidia-smi vgpu -h

Another common switch I use on the ESXi host with vGPU for troubleshooting is: “nvidia-smi -q”, which provides lots of information on the physical GPU in the host:

[[email protected]:~] nvidia-smi -q

==============NVSMI LOG==============

Timestamp                                 : Sat Mar  4 21:26:18 2023
Driver Version                            : 525.85.07
CUDA Version                              : Not Found
vGPU Driver Capability
        Heterogenous Multi-vGPU           : Supported

Attached GPUs                             : 1
GPU 00000000:04:00.0
    Product Name                          : NVIDIA A2
    Product Brand                         : NVIDIA
    Product Architecture                  : Ampere
    Display Mode                          : Enabled
    Display Active                        : Disabled
    Persistence Mode                      : Enabled
    vGPU Device Capability
        Fractional Multi-vGPU             : Not Supported
        Heterogeneous Time-Slice Profiles : Supported
        Heterogeneous Time-Slice Sizes    : Not Supported
    MIG Mode
        Current                           : N/A
        Pending                           : N/A
    Accounting Mode                       : Enabled
    Accounting Mode Buffer Size           : 4000
    Driver Model
        Current                           : N/A
        Pending                           : N/A
    Serial Number                         : XXXN0TY0SERIALZXXX
    GPU UUID                              : GPU-de23234-3450-6456-e12d-bfekgje82743a
    Minor Number                          : 0
    VBIOS Version                         : 94.07.5B.00.92
    MultiGPU Board                        : No
    Board ID                              : 0x400
    Board Part Number                     : XXX-XXXXX-XXXX-XXX
    GPU Part Number                       : XXXX-XXX-XX
    Module ID                             : 1
    Inforom Version
        Image Version                     : G179.0220.00.01
        OEM Object                        : 2.0
        ECC Object                        : 6.16
        Power Management Object           : N/A
    GPU Operation Mode
        Current                           : N/A
        Pending                           : N/A
    GSP Firmware Version                  : N/A
    GPU Virtualization Mode
        Virtualization Mode               : Host VGPU
        Host VGPU Mode                    : SR-IOV
        Relaxed Ordering Mode             : N/A
        Bus                               : 0x04
        Device                            : 0x00
        Domain                            : 0x0000
        Device Id                         : 0x25B610DE
        Bus Id                            : 00000000:04:00.0
        Sub System Id                     : 0x157E10DE
        GPU Link Info
            PCIe Generation
                Max                       : 3
                Current                   : 1
                Device Current            : 1
                Device Max                : 4
                Host Max                  : N/A
            Link Width
                Max                       : 16x
                Current                   : 8x
        Bridge Chip
            Type                          : N/A
            Firmware                      : N/A
        Replays Since Reset               : 0
        Replay Number Rollovers           : 0
        Tx Throughput                     : 0 KB/s
        Rx Throughput                     : 0 KB/s
        Atomic Caps Inbound               : N/A
        Atomic Caps Outbound              : N/A
    Fan Speed                             : 0 %
    Performance State                     : P8
    Clocks Throttle Reasons
        Idle                              : Active
        Applications Clocks Setting       : Not Active
        SW Power Cap                      : Not Active
        HW Slowdown                       : Not Active
            HW Thermal Slowdown           : Not Active
            HW Power Brake Slowdown       : Not Active
        Sync Boost                        : Not Active
        SW Thermal Slowdown               : Not Active
        Display Clock Setting             : Not Active
    FB Memory Usage
        Total                             : 16380 MiB
        Reserved                          : 264 MiB
        Used                              : 7808 MiB
        Free                              : 8306 MiB
    BAR1 Memory Usage
        Total                             : 16384 MiB
        Used                              : 1 MiB
        Free                              : 16383 MiB
    Compute Mode                          : Default
        Gpu                               : 0 %
        Memory                            : 0 %
        Encoder                           : 0 %
        Decoder                           : 0 %
    Encoder Stats
        Active Sessions                   : 0
        Average FPS                       : 0
        Average Latency                   : 0
    FBC Stats
        Active Sessions                   : 0
        Average FPS                       : 0
        Average Latency                   : 0
    Ecc Mode
        Current                           : Disabled
        Pending                           : Disabled
    ECC Errors
            SRAM Correctable              : N/A
            SRAM Uncorrectable            : N/A
            DRAM Correctable              : N/A
            DRAM Uncorrectable            : N/A
            SRAM Correctable              : N/A
            SRAM Uncorrectable            : N/A
            DRAM Correctable              : N/A
            DRAM Uncorrectable            : N/A
    Retired Pages
        Single Bit ECC                    : N/A
        Double Bit ECC                    : N/A
        Pending Page Blacklist            : N/A
    Remapped Rows
        Correctable Error                 : 0
        Uncorrectable Error               : 0
        Pending                           : No
        Remapping Failure Occurred        : No
        Bank Remap Availability Histogram
            Max                           : 64 bank(s)
            High                          : 0 bank(s)
            Partial                       : 0 bank(s)
            Low                           : 0 bank(s)
            None                          : 0 bank(s)
        GPU Current Temp                  : 37 C
        GPU T.Limit Temp                  : N/A
        GPU Shutdown Temp                 : 96 C
        GPU Slowdown Temp                 : 93 C
        GPU Max Operating Temp            : 86 C
        GPU Target Temperature            : N/A
        Memory Current Temp               : N/A
        Memory Max Operating Temp         : N/A
    Power Readings
        Power Management                  : Supported
        Power Draw                        : 8.82 W
        Power Limit                       : 60.00 W
        Default Power Limit               : 60.00 W
        Enforced Power Limit              : 60.00 W
        Min Power Limit                   : 35.00 W
        Max Power Limit                   : 60.00 W
        Graphics                          : 210 MHz
        SM                                : 210 MHz
        Memory                            : 405 MHz
        Video                             : 795 MHz
    Applications Clocks
        Graphics                          : 1770 MHz
        Memory                            : 6251 MHz
    Default Applications Clocks
        Graphics                          : 1770 MHz
        Memory                            : 6251 MHz
    Deferred Clocks
        Memory                            : N/A
    Max Clocks
        Graphics                          : 1770 MHz
        SM                                : 1770 MHz
        Memory                            : 6251 MHz
        Video                             : 1650 MHz
    Max Customer Boost Clocks
        Graphics                          : 1770 MHz
    Clock Policy
        Auto Boost                        : N/A
        Auto Boost Default                : N/A
        Graphics                          : 650.000 mV
        State                             : N/A
        Status                            : N/A
        GPU instance ID                   : N/A
        Compute instance ID               : N/A
        Process ID                        : 2108966
            Type                          : C+G
            Name                          : VM-WS02
            Used GPU Memory               : 3904 MiB
        GPU instance ID                   : N/A
        Compute instance ID               : N/A
        Process ID                        : 2108989
            Type                          : C+G
            Name                          : VM-WS01
            Used GPU Memory               : 3904 MiB

As you can see, you can pull quite a bit of information in detail from the vGPU, as well as the VM processes.

Running “nvidia-smi” on the VM Guest

You can also run “nvidia-smi” inside of the guest VM, which will provide you information on the vGPU instance that is being provided to that specific VM, along with information on the guest VM’s processes that are utilizing the GPU.

Screenshot of "nvidia-smi" running on guest virtual machine VM
“nvidia-smi” Running on Guest VM

This is helpful for providing information on the guest VM’s usage of the vGPU instance, as well as processes that require GPU usage.

Virtual Machine log files

Each Virtual Machine has a “vmware.log” file inside of the VM’s folder on the datastore.

To identify logging events pertaining to NVIDIA vGPU, you can search for the “vmiop” string inside of the vmware.log file.


cat /vmfs/volumes/DATASTORE/VirtualMachineName/vmware.log | grep -i vmiop

The above will read out any lines inside of the log that have the “vmiop” string inside of them. The “-i” flag instructs grep to ignore case sensitivity.

This logs provide initialization information, licensing information, as well as XID error codes and faults.

ESXi Host log files

Additionally, since the ESXi host is running the vGPU Host Driver (vGPU Manager), it also has logs that pertain and assist with vGPU troubleshooting.

Some commands you can run are:

cat /var/log/vmkernel.log | grep -i vmiop
cat /var/log/vmkernel.log | grep -i nvrm
cat /var/log/vmkernel.log | grep -i nvidia

The above commands will pull NVIDIA vGPU related log items from the ESXi log files.

Using “dxdiag” in the guest VM

Microsoft has a tool called “dxdiag” which provides diagnostic infromation for testing and troubleshooting video (and sound) with DirectX.

I find this tool very handy for quickly verifying

Microsoft DirectX "dxdiag" showing information on vGPU
NVIDIA vGPU with Microsoft DirectX “dxdiag” tool

As you can see:

  • DirectDraw Acceleration: Enabled
  • Direct3D Acceleration: Enabled
  • AGP Texture Acceleration: Enabled
  • DirectX 12 Ultimate: Enabled

The above show that hardware acceleration is fully functioning with DirectX. This is a indicator that things are generally working as expected. If you have a vGPU and one of the first three is showing as disabled, then you have a problem that requires troubleshooting. Additionally, if you do not see your vGPU card, then you have a problem that requires troubleshooting.

Please Note: You may not see “DirectX 12 Ultimate” as this is related to licensing.

Using the “VMware Horizon Performance Monitor”

The VMware Horizon Performance Monitor, is a great tool that can be installed by the VMware Horizon Agent, that allows you to pull information (stats, connection information, etc) for the session. Please note that this is not installed by default, and must be selected when running the Horizon Agent installer.

When it comes to troubleshooting vGPU, it’s handy to use this too to confirm you’re getting H.264 or H.265/HEVC offload from the vGPU instance, and also get information on how many FPS (Frames Per Second) you’re getting from the session.

VMware Horizon Performance Monitor showing vGPU NVIDIA NvEnc HEVC as encoder type
VMware Horizon Performance Tracker with NVIDIA vGPU

Once opening, you’ll change the view above using the specified selector, and you can see what the “Encoder Name” is being used to encode the session.

Examples of GPU Offload “Encoder Name” types:

  • NVIDIA NvEnc HEVC 4:2:0 – This is using the vGPU offload using HEVC
  • NVIDIA NvEnc HEVC 4:4:4 – This is using the vGPU offload using HEVC high color accuracy
  • NVIDIA NvEnc H264 4:2:0 – This is using the vGPU offload using H.264
  • NVIDIA NvEnc H264 4:4:4 – This is using the vGPU offload using H.264 high color accuracy

Examples of Software (CPU) Session “Encoder Name” types:

  • BlastCodec – New VMware Horizon “Blast Codec”
  • h264 4:2:0 – Software CPU encoded h.264

If you’re seeing “NVIDIA NvEnc” in the encoder name, then the encoding is being offloaded to the GPU resulting in optimum performance. If you don’t see it, it’s most likely using the CPU for encoding, which is not optimal if you have a vGPU, and requires further troubleshooting.

NVIDIA vGPU Known Issues

Depending on the version of vGPU that you are running, there can be “known issues”.

When viewing the NVIDIA vGPU Documentation, you can view known issues, and fixes that NVIDIA may provide. Please make sure to reference the documentation specific to the version you’re running and/or the version that fixes the issues you’re experiencing.

Common Problems

There are a number of common problems that I come across when I’m contacted to assist with vGPU deployments.

Please see below for some of the most common issues I experience, along with their applicable fix/workaround.

XID Error Codes

When viewing your Virtual Machine VM or ESXi log file, and experiencing an XID error or XID fault, you can usually look up the error codes.

Typically, vGPU errors will provide an “XiD Error” code, which can be looked up on NVIDIA’s Xid Messages page here: XID Errors :: GPU Deployment and Management Documentation (

The table on this page allows you to lookup the XID code, find the cause, and also provides information if the issue is realted to “HW Error” (Hardware Error), “Driver Error”, “User App Error”, “System Memory Corruption”, “Bus Error”, “Thermal Issue”, or “FB Corruption”.

An example:

2023-02-26T23:33:24.396Z Er(02) vthread-2108265 - vmiop_log: (0x0): XID 45 detected on physical_chid:0x60f, guest_chid:0xf
2023-02-26T23:33:36.023Z Er(02) vthread-2108266 - vmiop_log: (0x0): Timeout occurred, reset initiated.
2023-02-26T23:33:36.023Z Er(02) vthread-2108266 - vmiop_log: (0x0): TDR_DUMP:0x52445456 0x00e207e8 0x000001cc 0x00000001
2023-02-26T23:33:36.023Z Er(02) vthread-2108266 - vmiop_log: (0x0): TDR_DUMP:0x00989680 0x00000000 0x000001bb 0x0000000f
2023-02-26T23:33:36.023Z Er(02) vthread-2108266 - vmiop_log: (0x0): TDR_DUMP:0x00000100 0x00000000 0x0000115e 0x00000000
2023-02-26T23:33:36.023Z Er(02) vthread-2108266 - vmiop_log: (0x0): TDR_DUMP:0x00000000 0x00000000 0x00001600 0x00000000
2023-02-26T23:33:36.023Z Er(02) vthread-2108266 - vmiop_log: (0x0): TDR_DUMP:0x00002214 0x00000000 0x00000000 0x00000000

2023-02-26T23:33:36.024Z Er(02) vthread-2108266 - vmiop_log: (0x0): TDR_DUMP:0x64726148 0x00736964 0x00000000 0x00000000
2023-02-26T23:33:36.068Z Er(02) vthread-2108265 - vmiop_log: (0x0): XID 43 detected on physical_chid:0x600, guest_chid:0x0

One can see XID code 45, as well as XID code 43, which after looking up on NVIDIA’s document, states:

  • XID 43 – GPU stopped processing
    • Possible Cause: Driver Error
    • Possible Cause: User App Error
  • XID 45 – Preemptive cleanup, due to previous errors — Most likely to see when running multiple cuda applications and hitting a DBE
    • Possible Cause: Driver Error

In the situation above, one can deduce that the issue is either Driver Error, Application Error, or a combination of both. In this specific case, you could try changing drivers to troubleshoot.

vGPU Licensing

You may experience issues in your vGPU deployment due to licensing issues. Depending on how you have you environment configured, you may be running in an unlicensed mode and not be aware.

In the event that the vGPU driver cannot obtain a valid license, it will run for 20 minutes with full capabilities. After that the performance and functionality will start to degrade. After 24 hours it will degrade even further.

Some symptoms of issues experienced when unlicensed:

  • Users experiencing laggy VDI sessions
  • Performance issues
  • Frames per Second (FPS) limited to 15 fps or 3 fps
  • Applications using OpenCL, CUDA, or other accelerated APIs fail

Additionally, some error messages and event logs may occur:

  • Event ID 2, “NVIDIA OpenGL Driver” – “The NVIDIA OpenGL driver has not been able to initialize a connection with the GPU.”
  • AutoCAD/Revit – “Hardware Acceleration is disabled. Software emulation mode is in use.”
  • “Guest is unlicensed”

Please see below for screenshots of said errors:

Additonally, when looking at the Virtual Machine VM vmware.log (inside of the VM’s folder on the ESXi datastore), you may see:

Guest is unlicensed. Cannot allocate more than 0x55 channels!
VGPU message 6 failed, result code: 0x1a

If this occurs, you’ll need to troubleshoot your vGPU licensing and resolve any issues occurring.

vGPU Type (vGPU Profile) mismatch

When using the default (“time-sliced”) vGPU deployment method, only a single vGPU type can be used on virtual machines or containers per physical GPU. Essentially all VMs or containers utilizing the physical GPU must use the same vGPU type.

If the physical GPU card has multiple GPUs (GPU chips), then a different type can be used on each physical GPU chip on the same card. 2 x GPUs on a single card = 2 different vGPU types.

Additionally, if you have multiple cards inside of a single host, the number of vGPU types you can deployed is based off the total number of GPUs across the total number of cards in your host.

If you configure multiple vGPU types and cannot support it, you will have issues starting VMs, as shown below:

Cannot power on VM with vGPU due to insufficient resources
Cannot power on VM with vGPU: Power on Failure, Insuffiecient resources

The error reads as follows:

Power On Failures

vCenter Server was unable to find a suitable host to power on the following virtual machines for the reasons listed below.

Insufficient resources. One or more devices (pciPassthru0) required by VM VDIWS01 are not available on host ESXi-Host.

Additionally, if provisioning via VMware Horizon, you may see: “NVIDIA GRID vGPU Support has detected a mismatch with the supported vGPUs”

Note: If you are using MIG (Multi Instance GPU), this does not apply as different MIG types can be applied to VMs from the same card/GPU.

vGPU or Passthrough with 16GB+ of Video RAM Memory

When attaching a vGPU to a VM, or passing through a GPU to a VM, with 16GB or more of Video RAM (Framebuffer memory), you may run in to a situation where the VM will not boot.

This is because the VM cannot map that large of memory space to be accesible for use.

Please see my blog post GPU or vGPU Passthrough with 16GB+ of video memory, for more information as well as the fix.

vGPU VM Freezes during VMware vMotion

Your users may report issues where their VDI guest VM freezes for a period of time during use. This could be caused due to VMware vMotion moving the virtual machine from one VMware ESXi host to another.

Please see my blog post NVIDIA vGPU VM Freezes during VMware vMotion: vGPU STUN Time for more information.

“ERR!” State

When experiencing issues, you may notice that “nvidia-smi” throws “ERR!” in the view. See the example below:

nvidia-smi showing ERR! error state on VMware ESXi host with vGPU
NVIDIA vGPU “nvidia-smi” reporting “ERR!”

This is an indicator that you’re in a fault or error state, and would recommend checking the ESXi Host log files, and the Virtual Machine log files for XID codes to identify the problem.

vGPU Driver Mismatch

When vGPU is deployed, drivers are installed on the VMware ESXi host (vGPU Manager Driver), as well as the guest VM virtual machine (guest VM driver).

Guest VM vGPU driver mismatch with VMware ESXi host
NVIDIA vGPU Driver Mismatch

These two drivers must be compatible with each other. As per NVIDIA’s Documentation, see below for compatibility:

  • NVIDIA vGPU Manager with guest VM drivers from the same release
  • NVIDIA vGPU Manager with guest VM drivers from different releases within the same major release branch
  • NVIDIA vGPU Manager from a later major release branch with guest VM drivers from the previous branch

Additionally, if you’re using the LTS (Long Term Support Branch), the additional compatibility note applies.

  • NVIDIA vGPU Manager from a later long-term support branch with guest VM drivers from the previous long-term support branch

If you have a vGPU driver mismatch, you’ll likely see Event ID 160 from “nvlddmkm” reporting:

NVIDIA driver version mismatch error: Guest driver is incompatible with host drive.

To resolve this, you’ll need to change drivers on the ESXi host and/or Guest VM to a supported combination.

Upgrading NVIDIA vGPU

When upgrading NVIDIA vGPU drivers on the host, you may experience issues or errors stating that the NVIDIA vGPU modules or services are loaded and in use, stopping your ability to upgrade.

Normally an upgrade would be preformed by placing the host in maintenance mode and running:

esxcli software vib update -d /vmfs/volumes/DATASTORE/Files/vGPU-15/

However, this fails due to modules that are loaded and in use by the NVIDIA vGPU Manager Services.

Before attempting to upgrade (or uninstall and re-install), place the host in maintenance mode and run the following command:

/etc/init.d/nvdGpuMgmtDaemon stop

This should allow you to proceed with the upgrade and/or re-install.

VMware Horizon Black Screen

If you experiencing a blank or black screen when connecting to a VDI session with an NVIDIA vGPU on VMware Horizon, it may not even be related to the vGPU deployment.

To troubleshoot the VMware Horizon Black Screen, please review my guide on how to troubleshoot a VMware Horizon Blank Screen.

VM High CPU RDY (High CPU Ready)

CPU RDY (CPU Ready) is a state when a VM is ready and waiting to be scheduled on a physical host’s CPU. In more detail, the VM’s vCPUs are ready to be scheduled on the ESXi host’s pCPUs.

In rare cases, I have observed situations where VMs with a vGPU and high CPU RDY times, experience instability. I believe this is due to timing conflicts with the vGPU’s time slicing, and the VM’s CPU waiting to be scheduled.

To check VM CPU RDY, you can use one of the following methods:

  1. Run “esxtop” from the CLI using the console or SSH
  2. View the hosts performance stats on vCenter
    • Select host, “Monitor”, “Advanced”, “Chart Options”, de-select all, select “Readiness Average %”

When viewing the CPU RDY time in a VDI environment, generally we’d like to see CPU RDY at 3 or lower. Anything higher than 3 may cause latency or user experience issues, or even vGPU issues at higher values.

For your server virtualization environment (non-VDI and no vGPU), CPU Ready times are not as big of a consideration.

vGPU Profiles Missing from VMware Horizon

When using newer GPUs with older versions of VMware Horizon, you may encounter an issue with non-persistent instant clones resulting in a provisioning error.

This is caused by missing vGPU Types or vGPU Profiles, and requires either downloading the latest definitions, or possibly creating your own.

For more information on this issue, please see my post NVIDIA A2 vGPU Profiles Missing from VMware Horizon causing provision failure.

Please see these these additional external links and resources which may assist.

Oct 302022
vGPU nvidia-smi GPU Link Info

If you’re like me, you want to make sure that your environment is as optimized as possible. I recently noticed that my NVIDIA A2 vGPU was reporting the vGPU PCIe Link Speed and Generation that the card was using was below what it was supposed to be running at on my VMware vSphere ESXi host.

I needed to find out if this was being reported incorrectly, if there was an issue, or something else effecting this. In my case, the specific GPU I was using is supposed to support PCIe Gen4, and has a physical connector supporting 4x, my host has PCIe Gen3 slots, so I should at least be getting Gen3 speeds.


The Problem

When running the command “nvidia-smi -q”, the GPU was reporting that it was only running at PCIe Gen 1 speeds, as shown below:

        GPU Link Info
            PCIe Generation
                Max                       : 3
                Current                   : 1
                Device Current            : 1
                Device Max                : 4
                Host Max                  : N/A
            Link Width
                Max                       : 16x
                Current                   : 8x

Something else worth noting, is that the card states that it supports a 16x interface, when it actually only physical has a 8x connector. I believe they use this chip on another board that has multiple GPUs on a single board that actually supports 16x.

You could say I was quite puzzled. Why would the card only be running at PCIe Generation 1 speeds? I thought it could be any of the scenarios below:

  • Dynamic mode that alternates when required (possibly for power savings)
  • Hardware issue
  • Hardware Limitation (I’m using this in an older server)
  • Software issues
  • Configuration issue

Unfortunately, when searching the internet, I couldn’t find many references to this metric, however I did find references from other user’s copy/pastes of “nvidia-smi -q” which had the same values (running PCIe Gen1), even with beefier and more high-end cards.

The Solution

After some more searching, I finally came across an NVIDIA technical document titled “Useful nvidia-smi Queries” that states that the current PCIe Generation Link speed “may be reduced when the GPU is not in use”. This confirms that it’s dynamic and adjusts when needed.

Finally, I decided to give some games a shot in a couple of the VMs, and to my surprise when running a game, the “Device Current” and “Current” PCIe Generation changed to PCIe Gen3 (note that my server isn’t capable of PCIe Gen4, which is the cards maximum), as shown below:

        GPU Link Info
            PCIe Generation
                Max                       : 3
                Current                   : 3
                Device Current            : 3
                Device Max                : 4
                Host Max                  : N/A
            Link Width
                Max                       : 16x
                Current                   : 8x

In conclusion, if you notice this in your environment, do not be alarmed as this is completely normal and expected behavior.

Oct 032022

When deploying automated desktop pools with NVIDIA vGPU on VMware Horizon with an NVIDIA A2 GPU, you may notice provisioning fails with an error.

Error during Provisioning Cloning of VM VM-NAME-01 has failed: Fault type is UNKNOWN_FAULT_FATAL - No GPU capable host available for provisioning VM-NAME-01 with profile nvidia_a2-4q. Please refer to VMware KB 59271 for more details.

Further, when visiting VMware KB 59271 and performing the instructions, provisioning still continues to fail.

Screenshot of error message Automated vGPU Desktop Pool fails to provision due to missing vGPU profiles
Automated vGPU Desktop Pool fails to provision due to missing vGPU profiles

Essentially, at present there is no “supported” to resolve this issue without applying the fix listed in this post. Additionally, if you’re a VMware customer with an active support agreement, I would recommend opening a ticket with VMware Support so that it can be addressed in a future release.

The Problem

The NVIDIA A2 GPU is fairly new, along with VMware vSphere support. Even newer, is the support for vGPU and VMware Horizon, requiring the latest drivers (vGPU Drivers versions 14.2 released August 2022) to enable vGPU profiles for the card.

After troubleshooting this, I noted that the “” file in “C:\Program Files\VMware\VMware View\Server\broker\conf” did not contain any NVIDIA A2 vGPU Profiles. Additionally, the file available on the VMware KB was also missing these profiles.

The Fix

To fix this, I referenced the NVIDIA vGPU User Guide to note the vGPU profiles allowed on the card, and created my own entries for the configuration file.

After adding these entries, restarting the server (or service), I was able to provision NVIDIA A2 enabled vGPU desktop pools.

To resolve this issue, add the following entries to your “” file in “C:\Program Files\VMware\VMware View\Server\broker\conf” (note, the contents of the file is case-sensitive):

# NVIDIA A2 Profiles
# Q-Series Virtual GPU Types for NVIDIA A2

# B-Series Virtual GPU Types for NVIDIA A2

# C-Series Virtual GPU Types for NVIDIA A2

# A-Series Virtual GPU Types for NVIDIA A2

After restarting the server or services, you should now be able to use the NVIDIA A2 vGPU profiles with VMware Horizon automated (vGPU) desktop pools.

You should be able to use this fix for other new vGPU cards that have been recently released where the profiles have not been configured for Horizon. VMware is likely to fix this in future released of VMware Horizon.

Sep 042022

When either directly passing through a GPU, or attaching an NVIDIA vGPU to a Virtual Machine on VMware ESXi that has more than 16GB of Video Memory, you may run in to a situation where the VM fails to boot with the error “Module ‘DevicePowerOn’ power on failed.”. Special considerations are required when performing GPU or vGPU Passthrough with 16GB+ of video memory.

This issue is specifically caused by memory mapping a GPU or vGPU device that has 16GB of memory or higher, and could involve both the host system (the ESXi host) and/or the Virtual Machine configuration.

In this post, I’ll address the considerations and requirements to passthrough these devices to virtual machines in your environment.

In the order of occurrence, it’s usually VM configuration related, however if the recommendations in the “VM Configuration Considerations” section do not resolve the issue, please proceed to reviewing the “ESXi Host Considerations” section.

Please note that if the issue is host related, other errors may be present, or the device may not even be visible to ESXi.

VM GPU and vGPU Configuration Considerations

First and foremost, all new VMs should be created using the “EFI” Firmware type. EFI provides numerous advantages in device access and memory mapping versus the older style “BIOS” firmware types.

VM Firmware type EFI

To do this, create a new virtual machine, navigate to “VM Options”, expand “Boot Options”, and confirm/change the Firmware to “EFI”. I recommend this for all new VMs, and not only for VMs accessing GPUs or vGPUs with over 16GB of memory. Please note that you shouldn’t change an existing VM, and should do this on a fresh new VM.

With performing GPU or vGPU Passthrough with 16GB+ of video memory, you’ll need to create a couple of entries under “Advanced” settings to properly configure access to these PCIe devices and provide the proper environment for memory mapping. The lack of these settings is specifically what causes the “Module ‘DevicePowerOn’ power on failed.” error.

Under the VM settings, head over to “VM Options”, expand “Advanced” and click on “Edit Configuration”, click on “Add Configuration Params”, and add the following entries:


Example below:

VM GPU and vGPU Memory Settings for 16GB or higher memory mapping

You’ll notice that while our GPU or vGPU profile may have 16GB of memory, we need to double that value, and set it for the “pciPassthru.64bitMMIOSizeGB” variable. If your card or vGPU profile had 32GB, you’d set it to “64”.

Additionally if you were passing through multiple GPUs or vGPU devices, you’d need to factor all the memory being mapped, and double the combined amount.

ESXi GPU and vGPU Host Considerations

On most new and modern servers, the host level doesn’t require any special configuration as they are already designed to pass through such devices to the hypervisor properly. However in some special cases, and/or when using older servers, you may need to modify configuration and settings in the UEFI or BIOS.

If setting the VM Configuration above still results in the same error (or possibly other errors), than you most likely need to make modifications to the ESXi hosts BIOS/UEFI/RBSU to allow the proper memory mapping of the PCIe device, in our case being the GPU.

This is where things get a bit tricky because every server manufacturer has different settings that will need to be configured.

Look for the following settings, or settings with similar terminology:

  • “Memory Mapping Above 4G”
  • “Above 4G Decoding”
  • “PCI Express 64-Bit BAR Support”
  • “64-Bit IOMMU Mapping”

Once you find the correct setting or settings, enable them.

Every vendor could be using different terminology and there may be other settings that need to be configured that I don’t have listed above. In my case, I had to go in to a secret “SERVICE OPTIONS” menu on my HPE Proliant DL360p Gen8, as documented here.

After performing the recommendations in this guide, you should now be able to passthrough devices with over 16GB of memory.

Additional Resources:

Jun 182022
Nvidia GRID Logo

When performing a VMware vMotion on a Virtual Machine with an NVIDIA vGPU attached to it, the VM may freeze during migration. Additionally, when performing a vMotion on a VM without a vGPU, the VM does not freeze during migration.

So why is it that adding a vGPU to a VM causes it to become frozen during vMotion? This is referred to as the VM Stun Time.

I’m going to explain why this happens, and what you can do to reduce these STUN times.

VMware vMotion

First, let’s start with traditional vMotion without a vGPU attached.

VMware vMotion with vSphere and ESXi
VMware vMotion with vSphere

vMotion allows us to live migrate a Virtual Machine instance from one ESXi host, to another, with (visibly) no downtime. You’ll notice that I put “visibly” in brackets…

When performing a vMotion, vSphere will migrate the VM’s memory from the source to destination host and create checkpoints. It will then continue to copy memory deltas including changes blocks after the initial copy.

Essentially vMotion copies the memory of the instance, then initiates more copies to copy over the changes after the original transfer was completed, until the point where it’s all copied and the instance is now running on the destination host.

VMware vMotion with vGPU

For some time, we have had the ability to perform a vMotion with a VM that as a GPU attached to it.

VMware vSphere with NVIDIA vGPU
VMware VMs with vGPU

However, in this situation things work slightly different. When performing a vMotion, it’s not only the system RAM memory that needs to be transferred, but the GPU’s memory (VRAM) as well.

Unfortunately the checkpoint/delta transfer technology that’s used with then system RAM isn’t available to transfer the GPU, which means that the VM has to be stunned (frozen) to stop it so that the video RAM can be transferred and then the instance can be initialized on the destination host.


The STUN time is essentially the time it takes to transfer the video RAM (framebuffer) from one host to another.

When researching this, you may find examples of the time it takes to transfer various sizes of VRAM. An example would be from VMware’s documentation “Using vMotion to Migrate vGPU Virtual Machines“:

NVIDIA vGPU Estimated STUN Times
Expected STUN Times for vMotion with vGPU on 10Gig vMotion NIC

However, it will always vary depending on a number of factors. These factors include:

  • vMotion Network Speed
  • vMotion Network Optimization
    • Multi-NIC vMotion to utilize multiple NICs
    • Multi-vmk vMotion to optimize and saturate single NICs
  • Server Load
  • Network Throughput
  • The number of VM’s that are currently being migrated with vMotion

As you can see, there’s a number of things that play in to this. If you have a single 10Gig link for vMotion and you’re migrating many VMs with a vGPU, it’s obviously going to take longer than if you were just migrating a single VM with a vGPU.

Optimizing and Minimizing vGPU STUN Time

There’s a number of things we can look at to minimize the vGPU STUN times. This includes:

  • Upgrading networking throughput with faster NICs
  • Optimizing vMotion (Configure multiple vMotion VMK adapters to saturate a NIC)
  • Configure Multi-NIC vMotion (Utilize multiple physical NICs to increase vMotion throughput)
  • Reduce DRS aggressiveness
  • Migrate fewer VMs at the same time

All of the above can be implemented together, which I would actually recommend.

In short, the faster we migrate the VM, the less the STUN Time will be. Check out my blog post on Optimizing VMware vMotion which includes how to perform the above recommendations.

Hope this helps!