HP ProCurve 2910al Access Security Manual page 140

TACACS+ Authentication
Configuring TACACS+ on the Switch
Figure 4-4. Advanced TACACS+ Settings Section of the TACACS+ Server User Setup
4-14
numbers 0 through 15, with zero allowing only Operator privileges (and
requiring two logins) and 15 representing root privileges. The root privilege
level is the only level that will allow Manager level access on the switch.
Then scroll down to the section that begins with "Shell" (See Figure 4-5).
Check the Shell box.
Check the Privilege level box and set the privilege level to 15 to allow "root"
privileges. This allows you to use the single login option.