Use the command-line tool - vsantop - that runs on ESXi hosts to view the real time vSAN performance metrics. You can use this tool to monitor vSAN performance.

To display the different performance views and metrics in vsantop, enter the following commands:
Command Description
^L Redraw screen
Space Update display
h or ? Help; show this text
q Quit
f/F Add or remove fields
o/O Change the order of displayed fields
s Set the delay in seconds between updates
# Set the number of instances to display
E Change the selected entity type
L Change the length of the field
l Limit display to specific node id
. Sort by column, same number twice to change sort order