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Figure 1. GPT partition table scheme
Figure 2 on the following page shows a comparison of the MBR and GPT layouts.
Protective MBR
Primary GPT Header
Entries 1 thru 4
Entries 5 – 128
Partition 1
Partition 2
Remaining Partitions
Entries 1 thru 4
Entries 5 – 128
Secondary GPT Header
Protects MBR-based
disk utilities
from overwriting
GPT drives
Defines usable
blocks on the disk
List of drive
partition entries
(up to 128)
Drive partitions
(up to 128)
Secondary/backup
GPT header and
partition entries
LBA = 512 bytes
NOTE: LBA -34 refers to the 34
th
addressable block
address counted backwards from the last LBA on
the drive.
Primary GPT
Secondary GPT
LBA 0
LBA 1
LBA 2
LBA 3
LBA -34
LBA 34
LBA -33
LBA -2
LBA -1