Installing ESXi on a supported USB flash drive or SD flash card
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Installing ESXi on a supported USB flash drive or SD flash card


Article ID: 310085


Updated On:


VMware vSphere ESXi


This article provides instructions for installing ESXi on a USB drive or SD flash card. However, certain considerations must be made before proceeding with an installation. Ensure that the USB flash drive or SD flash card you are using is supported for installation of ESXi 5.5, ESXi 6.x and ESXi 7.x, consult your server vendor for the appropriate choice of a USB or SD flash storage device.
Note: In the event that your original SD flash card or USB drive fails, these steps can be used in a disaster recovery capacity to get a fully functional ESXi host running as quickly as possible on a replacement USB drive or SD flash card.


VMware vSphere ESXi 5.5
VMware vSphere ESXi 6.5
VMware vSphere ESXi 7.0.0
VMware vSphere ESXi 6.7
VMware vSphere ESXi 6.0


Installing ESXi on to a USB flash drive or SD flash card

Note: Installing ESXi on a USB flash drive or SD flash card has the same minimum requirements as installing to typical SCSI or SATA hard disk. For more information, see the minimum requirements section in the vSphere 5.x Documentation Center and ESXi Hardware Requirements.
  1. Acquire and create an installation CD/DVD by downloading ESXi from the VMware Download Center and burn the ISO file onto CD/DVD media.
Note: Some server hardware supports directly mounting ISO to Virtual CD/DVD-ROM (Eg. HP ILO), burning ISO to CD/DVD and inserting CD (Step 2) is not required in those situations.
  1. Insert the ESXi install able CD into the CD/DVD-ROM drive.
  2. Press the key required to activate your machine's BIOS setup. This key is often a function key or the Delete key. For more information, consult your hardware vendor documentation.
  3. Ensure that you have set the BIOS to boot from a CD/DVD-ROM device. This varies based on manufacturer.
  4. Start the ESXi Installation CD/DVD media.
  5. Let the Automatic boot countdown and boot as normal.The ESXi installation process begins and you see that the kernel modules and drivers are loaded.The installation continues to load at a yellow screen.
  6. Wait for the installation to load completely.
  7. After you see the Welcome screen, click Enter to continue with the installation.
  8. Read the End-User License Agreement (EULA) and press F11 if you accept.

    The installer detects the disks available for installation. If it sees the flash drive, it is presented as USB under type, and the model as flash reader.
  9. Select this device to install ESXi and press Enter. If the device is not listed, ensure that your machine sees the device and that the device is compatible. For more information, see the vSphere Compatibility Matrix.
  10. Select the keyboard layout. This is usually Default.
  11. Enter the root password you want. VMware recommends that you do not leave this blank.

    The installation begins and may take up to 15 minutes.
  12. When the installation completes, remove the installation CD/DVD-ROM.
  13. Click Enter to reboot the host.
  14. Set the first boot device to be the drive on which you installed ESXi on to the USB flash drive or SD flash card.

Limitation when installing on USB flash drive or SD flash card:

Due to the I/O sensitivity of USB and SD devices the installer does not create a scratch partition on these devices. When installing on USB or SD devices, the installer attempts to allocate a scratch region on an available local disk or datastore. If no local disk or datastore is found, /scratch is placed on the ramdisk. After the installation, you should reconfigure /scratch to use a persistent datastore. For more information, see Creating a persistent scratch location for ESXi 4.x and 5.x (1033696). VMware recommends using a retail purchased USB flash drive of 16 GB or larger so that the "extra" flash cells can prolong the life of the boot media but high quality parts of 4 GB or larger are sufficient to hold the extended coredump partition.

To workaround this limitation:
  1. Connect to the ESXi host via SSH. For more information, see Using Tech Support Mode in ESXi 4.1 and ESXi 5.x (1017910).
  2. Back up the existing boot.cfg file, located in /bootbank/, using this command:

    cp /bootbank/boot.cfg /bootbank/boot.bkp
  3. Open the boot.cfg file using VI editor. For more information, see Editing files on an ESX host using vi or nano (1020302).
  4. Modify the following line:



    kernelopt=autoPartition=TRUE skipPartitioningSsds=TRUE autoPartitionCreateUSBCoreDumpPartition=TRUE allowCoreDumpOnUsb=TRUE 
  5. Save and close the boot.cfg file.
  6. Restart the ESXi host.

Additional Information

For more information, see the Install, Upgrade, or Migrate ESXi from a USB Flash Drive Using a Script section of the VMware vSphere ESXi and vCenter Server 5.1 Documentation Guide.

VMware does not have a specific list of supported SD cards because VMware rely on the support of SD card by the host hardware. Therefore, VMware support SD cards only under these conditions:
  • The server on which you want to install ESXi is listed on the VMware Compatibility Guide and you have purchased a server with Embedded ESXi on the server from a certified vendor.
  • You have used a SD flash device that is approved by the server vendor for the particular server model on which you want to install ESXi on a SD flash storage device.

Note: If you intend to install ESXi on a SD flash storage device while ensuring VMware support for it and you have not purchased a server with Embedded ESXi, consult your server vendor for the appropriate choice of a SD flash storage device.


Disaster Recovery Scenario

If you have a local datastore containing production information and have completed the installation on a replacement USB flash drive or SD flash card in a disaster recovery scenario, you may be required perform these additional steps:

  1. Connect to the ESXi host using the vSphere Client or add the ESXi host to an existing vCenter Server implementation.
  2. Click the host.
  3. Click the Configuration tab.
  4. Click Storage.
  5. Click Rescan to ensure you can see all datastores.
  6. Browse the datastore and register any virtual machines that are located on the datastores. For more information, see Registering or adding a virtual machine to the inventory (1006160).