Asus TS300-PA4 - Manual (Page 157)

ASUS TS300-E3/PA4 & PS4 6-29
6.2.8 Selecting the boot drive from a RAID set
You must have created a new RAID configuration before you can select the
boot drive from a RAID set. Refer to the Creating a RAID set: Using New
Configuration section for details.
To select the boot drive from a RAID set:
1. From the Management Menu, select Configure > Select Boot Drive, then
press <Enter>.
2. When prompted, press the <SpaceBar> to select the bootable logical drive
from the list, then press <Enter>.
3. The logical drive is selected as boot drive. Press any key to continue.