Since you mentioned you have ClearPass I'd recommend TACACS+
Get your clock right:
ntp server <Your NTP Server> iburst version 3 prefer
ntp server <Your NTP Server 2 > iburst version 3
clock timezone <Your Time Zone>
ntp enable
Configure TACACS:
tacacs-server host <ClearPass 1> key plaintext <PSK> vrf default
tacacs-server host <ClearPass 2> key plaintext <PSK> vrf default
aaa group server tacacs ClearPass-TACACS
server <ClearPass 1> vrf default
server <ClearPass 2> vrf default
aaa authentication login console group ClearPass-TACACS local
aaa authentication login default group ClearPass-TACACS local
aaa authentication login ssh group ClearPass-TACACS local
aaa accounting all-mgmt default start-stop group ClearPass-TACACS local
Keep in mind 10.11 is a short term support release, end of support this November so if you're deploying 80 you may want to go with the 10.10 code.
For some additional reference check out the Aruba Solutions Exchange Solution 126 "ArubaOS-Switch TACACS+ RADIUS MGMT with ClearPass"
https://ase.arubanetworks.com/solutions/id/126