Partition Record Technical Details

Different operating systems have different Partition Type bytes. The most common DOS partition type is 6h, which is used for Primary DOS partitions greater than 32 Mbytes.

Here is a list of known (and suspected) partition type bytes:

  • 00 Not Occupied
  • 01 DOS, Primary Partition (12-bit FAT, <16MB)
  • 02 XENIX root
  • 03 XENIX usr
  • 04 DOS, Primary Partition (16-bit FAT, >=16MB and <32MB)
  • 05 DOS, Extended Partition
  • 06 DOS, Primary Partition (16-bit FAT, >32MB)
  • 07 OS/2 HPFS, Win NTFS, QNX ver 2, or Adv UNIX
  • 08 AIX – boot
  • 09 AIX – data, Coherent
  • 0A OS/2 BtMgr
  • 0B PRI DOS 512 Mbytes – 2 Tbytes FAT32 Win95, OSR2 & 98
  • 0C EXT DOS 512 Mbytes – 2 Tbytes FAT32 Win95, OSR2 & 98
  • 0E PRI DOS 32 Mbytes-2 Gbytes FAT16 Windows 95 & 98
  • 0F EXT DOS 0-2 Gbytes Windows 95 & 98
  • 10 OPUS
  • 12 Compaq diagnostics partition
  • 40 VENIX 80286
  • 50 DiscWizard Starter Edition read only DOS partition
  • 51 DiscWizard Starter Edition read/write DOS partition
  • 52 CPM, Microport System V/386
  • 54 DiscWizard Starter Edition non-DOS partition
  • 55 Micro House EZ-Drive ® non-DOS partition
  • 56 Golden Bow Vfeature partition
  • 61 Storage Dimensions SpeedStor partition
  • 63 UNIX – AT&T System V/386
  • 64 Novell NetWare 286
  • 65 Novell NetWare 386
  • 75 PC/IX IBM
  • 77 QNX POSIX partition
  • 78 QNX POSIX partition (secondary)
  • 79 QNX POSIX partition (secondary)
  • 80 Minix (v1.4a and earlier)
  • 81 Minix (v1.4b and later), Linux
  • 82 Linux swap partition
  • 83 Linux native file system
  • 93 Amoeba file system
  • 94 Amoeba bad block table?
  • DB Digital Research CPM-86, Concurrent DOS
  • E1 SpeedStor 12-bit FAT extended partition
  • E3 DOS read-only
  • E4 SpeedStor 16-bit FAT extended partition
  • F2 2nd DOS partition, some OEM customized DOS
  • F4 SpeedStor, large partitions
  • FE Lan Step, SpeedStor (partitions over 1024 cyl?)
  • FF UNIX bad block table partition

Related link: SCSI Sense Key Chart

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I have multiple partitions and my last partition regularly disappears

There are two workarounds for this phenomenon:

  1. Only use one primary DOS partition.
  2. Using FDISK, follow the steps below when partitioning the drive:
    1. Create a primary DOS partition with the desired size.
    2. Reboot
    3. Create an extended DOS partition using 99% of the available space remaining instead of 100%
    4. Reboot
    5. Create as many logical DOS drives as required, but with a reboot between each logical drive created.
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