Note: Not all systems are capable of booting from a USB device.
To boot from a USB device, settings in the BIOS need to be modified. The BIOS is most commonly accessed by pressing the “F2” button at the beginning of the boot sequence. In most cases, the system will show a message, such as “Press F2 to enter Setup,” to indicate the appropriate key (in this case, “F2”). A few other alternatives are “F1,” “Del,” “F9,” and “F11.” Watch the boot screen carefully as the BIOS usually displays the appropriate key.
Bootable USB devices can include a USB flash drive or a USB external hard drive. Depending on the system’s BIOS, a bootable USB flash drive may require separate BIOS settings than a bootable USB hard drive. The following example shows the settings from an HP ProLiant DL380 G5.
At the beginning of the DL380 boot sequence, a message indicates that “F9” must be pressed to enter setup. To ensure a system can boot from a USB device, choose “Standard Boot Order.” This option, sometimes found in the Advanced Options, will vary in location from BIOS to BIOS. The boot device order can be modified from this location. The dialog box below provides an option to boot from “USB DriveKey,” and it is assigned the highest boot priority level. This system is capable of booting from a USB device.
The BIOS might also include “USB hard drives” or “Removable Devices” in the boot device priority list. If the system is unable to boot from a USB drive/key, ensure that USB is enabled. The screenshot to the right displays the enable/disable USB options of the HP Proliant DL380. This applies to the host controller and to Legacy USB support.
Before modifying BIOS settings, write down the original settings and the new settings. This will prevent the need to restore the default BIOS settings.