What is the difference between primary partition and basic data partition?

I formatted two spare drives I have and am confused that the lower one says "basic data partition". How do I format it to primary partition? More importantly, does it make any difference?

screenshot here

4 Answers 4


What is the difference between primary partition and basic data partition?

The 2 drives are using different ways of storing the partitioning data:

  • Drives labelled "Primary Data Partition" use MBR (Master Boot Record) and won't boot on UEFI-only BIOS mode.

  • Drives labelled "Basic Data Partition" use GPT (GUID Partition Table) and won't boot on MBR BIOSes. This is the newer standard.

Further Reading: What's the Difference Between GPT and MBR When Partitioning a Drive?


  • 1
    Thanks, is GPT better because it's newer? In my case use (hook up to tv/use as network storage) will it make any difference whether it's MBR or GPT?
    – Noobcoder
    May 27 at 8:27
  • "Will it make any difference?" Only if you plan to boot off the drive.
    – DavidPostill
    May 27 at 8:35
  • 1
    @Noobcoder GPT is better because it has a 2 partition tables so you'll have a chance to backup data when a partition table is corrupted
    – phuclv
    May 27 at 15:05
  • @phuclv It's trivial to backup/restore an MBR table. 8 Free Tools to Backup and Restore the Master Boot Record (MBR) • Raymond.CC
    – DavidPostill
    May 27 at 15:10
  • DavidPostill, typically yes. But what about an encrypted Truecrypt/Veracrypt partition? :)
    – r2d3
    May 27 at 16:39

The first disk uses the MBR partition table format, the second one uses GPT.

MBR partition tables have a distinction between "Primary" partitions (defined directly in the 4 partition slots of the MBR) and "Logical" ones (defined in an extension within a primary partition). For GPT disks there's no such label as all partitions are primary and of equal status.

On the other hand, GPT partition tables have a "partition type" field that indicates its purpose, e.g. whether it's used for ordinary FAT/NTFS file storage or whether it's used for holding a recovery image – which is what you're seeing here in Disk Management. Your OS disk will probably have a "Recovery" partition and an "EFI System" partition. (Technically MBR also has such a field but it's limited to the point of being useless.)

If you can make the disk completely empty (delete all partitions), then right-clicking on the "Disk 0" will offer you an option to convert it to GPT partition table format, or the other way for Disk 1; then you can create new partitions again.

(The Linux gdisk tool can also convert disks with their partitions intact.)

More importantly, does it make any difference?

For data-only disks up to 2 TiB, it makes little difference as to which format you use – GPT is preferred in general, though some devices (e.g. older smart TVs) might not recognize it, in which case MBR is also okay.

For data disks larger than 2 TiB, GPT is the only option (unless I guess it's a 4K-native disk?).

For OS disks, the partition table format should generally match the PC firmware. Systems with UEFI firmware should have their OS installed in UEFI mode and use a GPT partition table. Similarly, BIOS boot usually goes with an MBR-partitioned disk. (UEFI in general does support booting from MBR partitioned disks, and likewise BIOS could technically boot from a GPT-partitioned disk, but e.g. Windows does not support such combinations, and it shouldn't be needed to do that in general. Some older BIOS systems required an MBR system disk for certain reasons.)

  • user1686, I disagree with "(defined in an extension within a primary partition)"
    – r2d3
    May 27 at 22:14

How do I format it to primary partition?

You would need to change the partition table scheme from GPT to MBR. I assume you would loose any existing data on this disk by doing that. Once having set the partition table scheme to MBR, you would create a new partition and format it.

More importantly, does it make any difference?

Yes it does, for instance from a recovery viewpoint. If the partition table(s) get lost, specialized software is able to rewrite the partition table. As writing more than one partition tables is required, incorrectly determined locations of partitions can cause partition data to be overwritten (worst case: one sector per partition). When rewriting a GPT partition table, write operation takes only place in a reserved area at the beginning and at the end of the disk. Incorrectedly located partitions will not trigger overwritten partition contents.

Recommendation: For data drives use GPT when your environment is compatible to this format.

Explanation of MBR partition table structure - by an example

MBR partition tables are realized by means of one or more linked partition tables located in sector 0 of the drive (to be correct, at LBA=0) and additional partition tables located between the data space occupied by the partitions.

This uncomfortable layout is the result of an extension of the old partition table format which had just one table allowing for four entries. As DOS 3.3 could not handle more than one primary partition the extension was defined.

The following list was created with the backup function of Testdisk, annotations in bold writing. It is a real example of a Windows XP boot disk containg three partitions, a primary and two logical ones.

#1653689348 Disk /dev/sdb - 120 GB / 111 GiB - CHS 14593 255 63

first partition table, at LBA=0

1 : start= 63, size= 4192902, Id=06, * C:-drive, Fat16
2 : start= 4192965, size=230243580, Id=05, E

second partition table, at LBA=4192965

5 : start= 4193028, size=210419307, Id=07, L D:-drive, NTFS
6 : start=214612335, size= 19824210, Id=05, X

third partition table, at LBA=214612335

6 : start=214612398, size= 19824147, Id=07, L drive without label, NTFS

At LBA=0 there is the first partition table. It contains the entries 1 and 2 above. The first entry points to a Fat16-Partition starting at LBA=63. The second entry at LBA=0 points to the second partition table at LBA=4192965. The first entry of the second partition table is pointing to my D:-drive. The second entry of the second partition table is pointing another partition table at LBA=214612335 The first entry of the third partition table is pointing to another NTFS-drive (without a label). There is no valid entry thereafter, here is, where the chain of partition table ends.

What the above does not show is that the nested partition table structure is sometimes referring to the first extended partition table and sometimes to the partition table before - it's a coding mess.

Comment on a statement by user1686

For data disks larger than 2 TiB, GPT is the only option (unless I guess it's a 4K-native disk?

Generally yes, except for the case of ready-to-use external drives with additional emulating electronics.

Example: Manufacturer has drive with native sectors of 4096 bytes, but the interface acts as if the sector size is 512 bytes. => 2 TB limit applies!

Manufacturer has 3TB drive with native sectors of 4096 bytes, but the interface acts as if the sector size is 512 bytes. Manufacturer puts in an additional emulating electronics making the drive appear with a sector size of 4096 bytes. => 3 TB can be addresses even with the MBR scheme. Disadvantage: When removing the drive for recovery, the drive geometry changes from 4096 bytes/sector to 512 bytes/sector.

28.5.2022 (rotating) hard drive market

sector size (internal) sector size (external) # models currently sold GPT required when >2TB
512 512 119 yes
4096 512 713 depends *1
4096 4096 72 no, when drive <= 16TB

*1 when adding additional translating electronics, like the one used in "ready-to-use" drives in external housings, GPT is not required
if size of disc / size of sector (external) < 2^32

=> Full 16 TB can be used
=> Only 16 TB can be used from a 18TB drive

Hint: In practice rising hard drive capacities have always disclosed problems in firmware and operating systems. To verify that your machine has no weak link in the chain create one big partition spanning your drive and run h2testw on Windows or f3 (fight flash fraud) on linux.

  • If it's a 4096 byte sector drive and its interface directly acts as if the sector is 4096 bytes, does that really count as "additional emulating electronics" if nothing is being emulated?
    – user1686
    May 28 at 7:16
  • No, I did not list all cases.
    – r2d3
    May 28 at 8:30
  • Added another section in my answer listing all case
    – r2d3
    May 28 at 9:01

primary partition = bootable, systems can boot from it

extended(data) partitions = not bootable, only to store data, systems can not boot from them

  • 2
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    – Community Bot
    May 27 at 11:59
  • 1
    Ciprian, the term "extended partition" originates from the old MBR world. The extended partition never carries data directly. It is just a hull to carry logical partitions. An "extended (data) partition" is a term I never heard of.
    – r2d3
    May 27 at 16:43
  • 100% agree with r2d3 statements
    – Ciprian
    May 29 at 7:09

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