1. GUID Partition Table Unified Extensible Firmware Interface (UEFI) GUID Partition Table (GPT)

2. Computer Center, CS, NCTU 2 Unified Extensible Firmware Interface  BIOS limitations 16-bit processor mode 1MB addressable space  UEFI advantages UEFI v2.3.1 in April 2011 Disk device compatibility (GUID Partition Table) Processor compatibility (x86, x64, ARM)

3. Computer Center, CS, NCTU 3 GUID Partition Table – (1)  Limitation of MBR partition table Partition record  active(1) 、 first CHS(3) 、 type(1) 、 last CHS(3) 、 start LBA(4) 、 size(4) Maximum capacity  (2 32 -1) x 512 bytes ~ 2 41 bytes = 2TBytes  GPT Maximum capacity: 8ZBytes (2 73 bytes) Used on some BIOS system

4. Computer Center, CS, NCTU 4 GUID Partition Table – (2)  GPT LBA 0: Legacy MBR LBA 1: GPT Header LBA 2~33: Partition Entries  128 partitions LBA 34~: Partitions LBA -34 ~ -1: Secondary GPT data  Misaligned block SSD (1K LBA) WD (4K sector)

5. Computer Center, CS, NCTU 5 GUID Partition Table – (3)  Legacy MBR (LBA 0) A single partition of type 0xEE, and of whole disk size (max 2T) For OSes which cannot read GPT: unknown partition, no space For GPT-aware OSes: check the “protective MBR”

6. Computer Center, CS, NCTU 6 GUID Partition Table – (4)  Partition header table (LBA 1) OffsetLengthContents 08 bytesSignature ("EFI PART", 45 46 49 20 50 41 52 54) 84 bytes Revision (For GPT version 1.0 (through at least UEFI version 2.3.1), the value is 00 00 01 00) 124 bytesHeader size in little endian (in bytes, usually 5C 00 00 00 meaning 92 bytes) 164 bytesCRC32 of header (0 to header size), with this field zeroed during calculation 204 bytesReserved; must be zero 248 bytesCurrent LBA (location of this header copy) 328 bytesBackup LBA (location of the other header copy) 408 bytesFirst usable LBA for partitions (primary partition table last LBA + 1) 488 bytesLast usable LBA (secondary partition table first LBA - 1) 5616 bytesDisk GUID (also referred as UUID on UNIXes) 728 bytesPartition entries starting LBA (always 2 in primary copy) 804 bytesNumber of partition entries 844 bytesSize of a partition entry (usually 128) 884 bytesCRC32 of partition array 92*Reserved; must be zeroes for the rest of the block (420 bytes for a 512-byte LBA)

7. Computer Center, CS, NCTU 7 GUID Partition Table – (5)  Partition header table (LBA 1) # dd if=/dev/ada0 bs=512 count=1 skip=1 | hd 00000000 45 46 49 20 50 41 52 54 00 00 01 00 5c 00 00 00 |EFI PART....\...| 00000010 e6 f0 27 96 00 00 00 00 01 00 00 00 00 00 00 00 |..'.............| 00000020 2f 60 38 3a 00 00 00 00 22 00 00 00 00 00 00 00 |/`8:....".......| 00000030 0e 60 38 3a 00 00 00 00 7f a3 90 90 46 b4 de 11 |.`8:........F...| 00000040 8e b8 00 21 85 12 22 74 02 00 00 00 00 00 00 00 |...!.."t........| 00000050 80 00 00 00 80 00 00 00 e0 9d 1a 52 00 00 00 00 |...........R....| 00000060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 00000200

8. Computer Center, CS, NCTU 8 GUID Partition Table – (6)  Partition entries (LBA 2~33) 128 bytes for each partition entry OffsetLengthContents 016 bytesPartition type GUID 1616 bytesUnique partition GUID 328 bytesFirst LBA (little-endian) 408 bytesLast LBA (inclusive, usually odd) 488 bytesAttribute flags (e.g. bit 60 denotes read-only) 5672 bytesPartition name (36 UTF-16LE code units) 128Total

9. Computer Center, CS, NCTU 9 GUID Partition Table – (7)  Partition type GUID freebsd-boot83BD6B9D-7F41-11DC-BE0B-001560B84F0F freebsd516E7CB4-6ECF-11D6-8FF8-00022D09712B freebsd-swap516E7CB5-6ECF-11D6-8FF8-00022D09712B freebsd-ufs516E7CB6-6ECF-11D6-8FF8-00022D09712B freebsd-vinum516E7CB8-6ECF-11D6-8FF8-00022D09712B freebsd-zfs516E7CBA-6ECF-11D6-8FF8-00022D09712B