Please note, Aruba AOS-CX switches can only establish VSF links via SFP ports. I assume the user knows which commands require configuration mode.

First verify that the switches are connected

sh int brief

sh lldp neighbor

On the primary member, set the VSF configuration. Port 1/1/28 on primary is connected to port 1/1/28 on the secondary.

vsf member 1
link 1 1/1/28

On the secondary member, set the following:

vsf member 1
link 1 1/1/28
exit
vsf renumber-to 2

The secondary member should reboot and attempt to form a VSF stack.

On the primary, renumber the second member after it joins the stack:

vsf secondary-member 2

On the primary, you can status with the following commands:

sh vsf
sh int brief
sh vsf top
sh vsf member 2