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GPT (GUID Partition Table) partitioning has some benefits over MBR (Master Boot Record), including Support for:

  1. More partitions (128)
  2. Drives larger than 2 TB

But are there any other benefits like less likelihood of corruption? (The two HD failures I've had were corrupt MBRs). Or are you just playing wack-a-mole where the GPT then gets corrupt in the same way?

Clay Nichols
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2 Answers2

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According to Wikipedia, there is redundancy in the GPT scheme. The GPT table is written at the beginning of the disk, as well as at the end of the disk (see image). In addition each GPT table has a CRC32 checksum.

enter image description here

The redundancy is not available in the MBR scheme (which only occupied the first 512 bytes of a disk). The extra redundancy would allow for more resilience against corruption. The CRC32 checksum allows the system to detect which of the two tables is the correct one to be used to repair the other.

nixda
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mtak
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The second copy of the partition table at the end of the device can have opposite effects, however:

Imagine you use a large disk that had GPT on it, and you decide to copy the image of a smaller GPT disk onto it (which was never a problem with MBR disks). The problem is that the software might locate the backup copy at the end of the device (i.e.: the obsolete partition table). Then both tables seem valid (CRC-wise), and the software might decide to use the one matching the disk size, copying the "backup" to the main one.

I was actually hit by such a problem when EFI and GPT were rather new.

U. Windl
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