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Can anyone tell me what the main differences between i.e. MBR vs GPT or any other partition scheme are? Why would one choose one over the other?


I am not an expert but from new release of Mac OS X which includes a feature called Time Machine, which I find highly useful. GPT is the requirement for Mac OS X Lion ... so on this basis I would say that GPT is more useful than MBR.

What other partition schemes are there and which one should be used in which situation?

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1  
I reworded your question to avoid it being closed as too subjective (i.e. not constructive). Asking "What is better" is not encouraged as you can read in the FAQ. –  slhck Aug 17 '11 at 20:58
    
@slhck thanks ... point to remember ... –  Safran Ali Aug 17 '11 at 21:01
    
In ubuntu theres option also to "Apple partition map" (havent tried it couse i think i dont need it until i use Apple) and "Dont partition" witch doesnt allow NTFS but can FAT (didnt tested other FS) but Dont partition partitioned disk doesnt work on Windows. –  Kangarooo Dec 23 '12 at 4:32

2 Answers 2

up vote 11 down vote accepted
  • Intel-based Macs all use EFI, and can only boot from GPT drives.

  • Booting from MBR is supported by all non-Mac x86 PCs. Booting from a GPT disk requires UEFI firmware.

    (This requirement doesn't apply for using MBR/GPT on data disks; in that case, only OS support is necessary.)

  • The MBR is 512 bytes in size; GPT can grow depending on partition count.

  • MBR uses the obsolete cylinder-head-sector addressing format, apparently.

  • There is only one MBR per disk. GPT keeps a backup copy.

  • MBR limits the whole disk to 2 TiB; in GPT the disk can be up to 16 EiB or 8 ZiB.

  • MBR is limited to four primary partitions. GPT can have 128 partitions.

  • To get around the MBR 4-partition limit, a partition can be an "extended partition" which contains a series of "logical partitions" but these logical partitions are only visible to OSs that recognize them. GPT doesn't need such workarounds.

  • The initial boot loader is part of the MBR. There can only be one bootloader in the MBR, resulting in conflicts when installing dual-boot systems. Due to the x86 DOS origins of the MBR bootloader, code is specific to the x86 architecture.

    On the other hand, GPT uses a dedicated FAT32 partition for bootloaders (potentially multiple) and other EFI tools. The partition contents can be easily managed from any OS.

  • MBR partitions have a one byte long "type" code, which is too small to be useful, so the type often has to be guessed by the OS. Windows NT introduced a four-byte unique ID, but this is non-standard.

    In GPT, each partition has a type GUID, an unique GUID for identifying the partition itself, and a textual name.

A more detailed info related to MBR and GPT:

Windows and GPT FAQ

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Given the Question's context of Macs, your original first bullet point was in error. I took the liberty of editing rather than downvoting. I hope you don't mind. –  Spiff Aug 17 '11 at 22:56
    
Most Intel-based Macs can boot from Apple Partition Map (APM)-formatted drives, but it's a secret so don't tell anyone. –  Gordon Davisson Aug 18 '11 at 2:35
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Since earlier this year, one can bootstrap in the old PC98 way with an EFI partitioned disc. –  JdeBP Aug 20 '11 at 4:14
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Well done for being the first to spot an almost 15-year-old error, by the way. 16EiB is of course the maximum file size with 64-bit file pointers, not volume or disc size with 64-bit sector numbers. 8ZiB is correct for the latter, according to the trusty log tables. –  JdeBP Aug 20 '11 at 4:22

I only know of three partition schemes: MBR, GPT, and APM. (These are the ones Apple's Disk Utility can create.)

MBR (Master Boot Record) is used historically by Windows (and, therefore, by most computer manufacturers). I'm not certain if you can boot a Mac from an MBR disk; I don't think so.

GPT (GUID Partition Table) is generally used in conjunction with Intel's EFI BIOS replacement. As such, it is mostly used by Apple currently in their Intel Macs. Any Mac running 10.4 or above can read a GPT disk; only Intel Macs can boot from them. If a computer has EFI, you can boot Windows on a GPT disk.

APM (Apple Partition Map) is what Apple used before the Intel switch. It's been used since 1989 in the Macintosh SE. Intel Macs can boot from and read APM disks.

I'd say the assertion you made in the question ("GPT is more useful than MBR") is incorrect: you can certainly boot more computers with an MBR disk than one using GPT. GPT is the way of the future, but it may take awhile for the major PC manufacturers to switch to EFI from BIOS.

Your Time Machine disk is almost certainly uses GPT, but that's totally irrelevant as you'll never boot from it.

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