After ESXi upgrading from 7.x to 8.0 U1 or later, Virtual Flash Cache cannot edit from vSphere Client

Products

• VMware vSphere ESXi

Issue/Introduction

• You configured Virtual Flash Cash on ESXi 7.x host local SSD device.
• ESXi host upgrade from 7.x to 8.0 U1 or later.
• You cannot edit it and see it via vSphere Client.
• There are still hostCache directory on upgraded ESXi 8.x host.

Environment

ESXi 8.0 U1 or later

Cause

vSphare 8.0 Update 1 or later adds a new file system type, VMFSOS specifically for the ESX-OSData system partition on local SSD devices.
This new file type prevents cases when you format an ESX-OSData volume on a local SSD device, and fsType returns a file of type Virtual Flash File System (VFFS). 
As a result, the disk backing of the ESX-OSData volume is listed under the Virtual Flash resources in vCenter.

Plase see VMware ESXi 8.0 Update 1 Release Notes

 

Resolution

You can remove the existing cache and re-create a Flash Cash to a new device.

Run the below commands to disable SwapToSSD via vsish 

# vsish -e ls /memory/llswap/dirs

This shows only 0 or 0, 1 and so on.

From this result, you run the below commands.

# vsish -e set /memory/llswap/dirs/0/sizeInBytes 0
# vsish -e set /memory/llswap/dirs/0/remove

or

# vsish -e set /memory/llswap/dirs/0/sizeInBytes 0
# vsish -e set /memory/llswap/dirs/0/remove
# vsish -e set /memory/llswap/dirs/1/sizeInBytes 0
# vsish -e set /memory/llswap/dirs/1/remove

and so on.

Additional Information

You can easily remove the Flash Cache settings via vSphere Client before upgrading to ESXi 8.0 U1 or later.