HP Pro 4300 GPT Hard Disk Drives for HP Business Desktops - Page 4

Protective MBR Primary GUID Partition Entry Array Basic MBR Disk Layout Basic GPT Disk Layout Master Boot Record Partition Table Extended Partition Master Boot Code 1st Partition Table Entry 2nd Partition Table Entry 3rd Partition Table Entry 4th Partition Table Entry 0x55 AA Primary Partition (C:) Primary Partition (E:) Primary Partition (F:) Logical Drive (G:) Logical Drive (H:) Logical Drive n Master Boot Code 1st Partition Table Entry 2nd Partition Table Entry 3rd Partition Table Entry 4th Partition Table Entry 0x55 AA Primary GUID Partition Table Header GUID Partition Entry 1 GUID Partition Entry 2 GUID Partition Entry n GUID Partition Entry 128 Primary Partition (C:) Primary Partition (E:) Primary Partition n GUID Partition Entry 1 GUID Partition Entry 2 GUID Partition Entry n GUID Partition Entry 128 Backup GUID Partition Table Header Figure 2. Comparison of MBR and GPT disk layouts Backup GUID Partition Entry Array Bootable vs Data Drives and UEFI BIOS Since the partitions on a data-storage drive are accessed by the OS and not the BIOS, GPT drives can be used on non-UEFI systems as data-storage drives. These drives cannot, however, be used as boot drives in such systems. The legacy BIOS in a non-UEFI system cannot find the boot information on a GPT-formatted drive and therefore cannot complete the boot process into the OS. In using a GPT drive as a data-storage drive, the drive must be formatted using tools that can create GPT partitions. In order to boot from a GPT-formatted drive, the system must have a UEFI BIOS. UEFI understands how to find the boot information on a GPT drive. In addition, the system must also have a "UEFI aware" OS such as Microsoft Windows 7 ™64-bit. For selected desktops, HP implements the Type 0 BIOS Information data structure (as described in version 2.7 of the SMBIOS specification) to indicate UEFI BIOS support. The BIOS Characteristics Extension Bytes field within this structure has defined a bit that, if set, identifies the system as UEFI compliant. Table 1 describes BIOS Characteristic Extension Byte 2, with Bit 3 identified as the bit for UEFI specification support. 4