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Fdisk shows multiple partition types. What is the difference between choosing 83) Linux and 8e) Linux LVM?

Choosing 83) Linux also works fine for using LVM, even creating a physical volume on /dev/sdb without a partition table works.

Does picking a partition type in fdisk really matter? What is the difference in picking Linux or Linux LVM as partition type?

[root@tst-01 ~]# fdisk /dev/sdb

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): l

 0  Empty           24  NEC DOS         81  Minix / old Lin bf  Solaris
 1  FAT12           39  Plan 9          82  Linux swap / So c1  DRDOS/sec (FAT-
 2  XENIX root      3c  PartitionMagic  83  Linux           c4  DRDOS/sec (FAT-
 3  XENIX usr       40  Venix 80286     84  OS/2 hidden C:  c6  DRDOS/sec (FAT-
 4  FAT16 <32M      41  PPC PReP Boot   85  Linux extended  c7  Syrinx
 5  Extended        42  SFS             86  NTFS volume set da  Non-FS data
 6  FAT16           4d  QNX4.x          87  NTFS volume set db  CP/M / CTOS / .
 7  HPFS/NTFS       4e  QNX4.x 2nd part 88  Linux plaintext de  Dell Utility
 8  AIX             4f  QNX4.x 3rd part 8e  Linux LVM       df  BootIt
 9  AIX bootable    50  OnTrack DM      93  Amoeba          e1  DOS access
 a  OS/2 Boot Manag 51  OnTrack DM6 Aux 94  Amoeba BBT      e3  DOS R/O
 b  W95 FAT32       52  CP/M            9f  BSD/OS          e4  SpeedStor
 c  W95 FAT32 (LBA) 53  OnTrack DM6 Aux a0  IBM Thinkpad hi eb  BeOS fs
 e  W95 FAT16 (LBA) 54  OnTrackDM6      a5  FreeBSD         ee  GPT
 f  W95 Ext'd (LBA) 55  EZ-Drive        a6  OpenBSD         ef  EFI (FAT-12/16/
10  OPUS            56  Golden Bow      a7  NeXTSTEP        f0  Linux/PA-RISC b
11  Hidden FAT12    5c  Priam Edisk     a8  Darwin UFS      f1  SpeedStor
12  Compaq diagnost 61  SpeedStor       a9  NetBSD          f4  SpeedStor
14  Hidden FAT16 <3 63  GNU HURD or Sys ab  Darwin boot     f2  DOS secondary
16  Hidden FAT16    64  Novell Netware  af  HFS / HFS+      fb  VMware VMFS
17  Hidden HPFS/NTF 65  Novell Netware  b7  BSDI fs         fc  VMware VMKCORE
18  AST SmartSleep  70  DiskSecure Mult b8  BSDI swap       fd  Linux raid auto
1b  Hidden W95 FAT3 75  PC/IX           bb  Boot Wizard hid fe  LANstep
1c  Hidden W95 FAT3 80  Old Minix       be  Solaris boot    ff  BBT
1e  Hidden W95 FAT1

Command (m for help):
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1 Answer

up vote 4 down vote accepted

The partition type byte is just that, a single byte in the MBR that holds a value that should relate to the partition layout inside the associated partition. It's really just a hint of what to methods to try when reading the partition. If you didn't have this the system would need to try to read the partition using a number of types - and obviously could get this wrong.

An analogy would be that if I read a phone number and it started with 001 or 044 I could start the conversion in English with a good chance of being understood from the start - it could be wrong but there's a good chance it would be ok. If it said 033 then I could assume that starting in French would be a good idea, 039 and I could try Italian first - and so on. Basically it's a strong-indicator, but only that - it can be wrong, of the underlying partition's type.

As to what the actual difference is between those two options - well that could go on to be a very long answer but essentially LVM deals with extents and has multiple additional layers of abstraction that clearly need to be considered during boot - whereas the standard Linux PT should be a lot more starightforward than LVM. Either way the booting kernel would benefit from knowing what to try first.

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Nice analogy - I'll remember that one! –  MadHatter Jul 2 '13 at 9:30
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