Is the EFI partition and GPT necessary with less than 2 TiB?

Question

I have a 1 TB external USB hard drive that is GUID partitioned with a 100MB FAT32 EFI partition.

The thing is that its a 1 terabyte drive. From what I'm aware, the limit is at 2 tebibytes (TiB). Therefore, the GPT isn't necessary, and MBR could be used instead.

TL;DR: What would happen if I delete the EFI partition and reformat as MBR partition table on an external drive not booted from?

Answer 1

What would happen if I delete the EFI partition and reformat as MBR partition table on an external drive not booted from?

Nothing. It would still just work.

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But you do seem to mix EFI and GPT, so let me give a longer answer:

MBR is a very old way of partitioning drives on a PC. It only allowed for four primary partitions, or, with a workaround, for 3 primary and several more "extended" partitions. It also tops out at 2.0 TiB (2³² 512 byte sectors), or 2.20 TB.

The GUID Partition Table (aka GPT), on the other hand, is a more modern way of dividing a drive into partitions. It allows for drives larger than 2 TiB, and it allows for way more partitions (up to 128 specifically).

There is nothing which stops you from selecting either method on a small enough drive. Both methods are valid. Any modern computer should be able to handle both of them, either via the BIOS or EUFI.

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There are three catches here though:

• If you use ancient software (e.g. Windows XP, which came out before the GPT scheme was created), then it will not understand GPT.
• If you use a old BIOS, then it may not understand GPT. (A modern BIOS should understand it, though there are quite a few which fail).
• If you partition a drive larger then 2.0 TiB with the MBR scheme, you will not be able to access anything past the 2 TiB mark. Your 1 TB drive, however, is small enough that this does not matter.