In the new command line window that opens, to determine the USB flash drive number or drive letter, at the command prompt,
The list disk command displays all the disks on the computer. Note the drive number or drive letter of the USB flash drive.
At the command prompt, type select disk <X>, where X is the drive number or drive letter of the USB flash drive, and then click ENTER.
If your server platform supports Unified Extensible Firmware Interface (UEFI), you should format the USB flash drive as FAT32 rather than as NTFS. To format the partition as FAT32, type format fs=fat32 quick, and then click ENTER.