Frequently asked Questions about Boot device guidance for low endurance media(vSphere and vSAN):

• Are USB-based boot devices being deprecated?
• What is supported for upgrades?
• What is supported for new installation?
• What is the plan to continue support for USB/SD boot for vSphere 7.0?
• What is the recommendation on using dual M.2 capability?
• What is the new partition scheme recommended since 7.0?

Are USB-based boot devices being deprecated?

• USB-based boot interfaces are not deprecated however VMware encourages use of M.2 and other SSDs for boot because of reliability concerns as outlined in the following section:

         "ESXi 7.0 Installation on M.2 and Other Non-USB Low-End Flash Media" of the document: ESXi Hardware Requirements

What is supported for upgrades?

• For all upgrades ESXi 7.0 onwards, we continue to support existing boot devices.
• We still allow upgrading on USB, however an extra disk with the USB device is recommended. 
• Having a low endurance device or a USB device might increase the risk of wear-out and might have unreliable outcomes. 
• In addition, having a low performance device will affect some features in future ESXi versions that may depend on performance.
• We strongly recommend upgrading to 32GB or higher high-endurance and high-performance devices for upgrades and new installations.

What is supported for new installation?

• For new installations, we strongly recommend using high performance and high endurance devices like M.2, SSDs etc. which is 32GB or greater.
• For all new installations, you must configure scratch to some persistent location (NFS or VMFS) in order for logs to be saved.

What is the recommendation if you already have these older devices?

• We recommend to install larger boot media. You should consider moving from USB/SDCard devices because high performance devices are required for predictable application behavior, some of them requiring larger and more reliable storage. Server OEM vendors to ensure the device meets the required endurance parameters provided in the guidance documentation.

What is the plan to continue support for USB/SD boot for vSphere 7.0?

• Apart from bootbanks being larger, 7.x  behavior is still the same as 6.x where things go to RAM disk if there's no high performance storage available
• The scratch partition can be configured elsewhere (eg. NFS) for logging, but isn't an ideal scenario
• As for supporting USB/SD devices, they can continue to use those devices, but they need to supply a secondary high-quality device. You can do this from the ESXi UI which allows them to delete datastores that are not in use or partedUtil to manually do it. For more information, please refer: Using the partedUtil command line utility on ESXi and ESX

Important: If you install ESXi on M.2 or other non-USB low-end flash media, delete the VMFS datastore on the device immediately after installation. For more information on removing VMFS datastores, see the vSphere Storage documentation

What is the recommendation from vSphere team on using dual M.2 capability?

• OEMs should ensure that ESXi only see a unified "single" boot device. Please contact your VMware representative.

What is the new partition scheme recommended since 7.0?

• Please refer to the following links:
• System Storage changes: vSphere 7 – System Storage When Upgrading

Additional reference material

• SSD & Flash Support KB: vSphere SSD and Flash Device Support
• Installing ESXi on a supported USB flash drive or SD flash card
• SATADOM devices and endurance: Using Boot Devices and vSAN
• Removal of SD card/USB as a standalone boot device option (85685) ​​​​