RHEL: GPT/MBR partition tables (using disks larger than 2 TiB)

# Tested on RHEL 6 & 7

# Up to now the default type of the partition table of a hard disk is MBR (msdos). This
# old method presents some problems like the limitation of having a maximum of four primary
# partitions but the main problem is that we can't go beyond the first 2 TiB of the disk.

# Nowadays physical disks are growing in size quickly. A way of solving this problem is
# by switching to GPT (GUID Partition Table) partitioning scheme.

# To partition a disk using GPT we first have to write a GPT label to it. The way to do
# it is the following:

parted /dev/<sde> mklabel gpt
   Warning: The existing disk label on /dev/sde will be destroyed and all data on this disk will be
   lost. Do you want to continue?
   Yes/No? Yes
   Information: You may need to update /etc/fstab.


# If we want to make the disk usable by LVM, first we have to partition the disk and mark
# the new partitions with the "LVM label" so let's create a new partition and change
# its name and flags

parted /dev/sde
   GNU Parted 3.1
   Using /dev/sde
   Welcome to GNU Parted! Type 'help' to view a list of commands.
   (parted) mkpart primary 1M 500M
   (parted) name 1 mypart
   (parted) p
   Model: ATA VBOX HARDDISK (scsi)
   Disk /dev/sde: 4295MB
   Sector size (logical/physical): 512B/512B
   Partition Table: gpt
   Disk Flags:

   Number  Start   End    Size   File system  Name    Flags
    1      1049kB  500MB  499MB               mypart

   (parted) set 1 lvm on
   (parted) p
   Model: ATA VBOX HARDDISK (scsi)
   Disk /dev/sde: 4295MB
   Sector size (logical/physical): 512B/512B
   Partition Table: gpt
   Disk Flags:

   Number  Start   End    Size   File system  Name    Flags
    1      1049kB  500MB  499MB               mypart  lvm

   (parted) q
   Information: You may need to update /etc/fstab.


# On RHEL 6, 'fdisk' is not able to manage disk partition table anymore:

myrhel6:/root#> fdisk -l /dev/sde
   WARNING: GPT (GUID Partition Table) detected on '/dev/sde'! The util fdisk doesn't support GPT. Use GNU Parted.
   [...]

# On RHEL 7, we get a message indicating that 'fdisk' support is in experimental phase:

myrhel7:/root#> fdisk -l /dev/sde
   WARNING: fdisk GPT support is currently new, and therefore in an experimental phase. Use at your own discretion.
   [...]


# To switch back to MBR partition table, do the the following:

parted /dev/<sde> mklabel msdos
   Warning: The existing disk label on /dev/sde will be destroyed and all data on this disk will be
   lost. Do you want to continue?
   Yes/No? Yes


Article Number: 70
Posted: Sun, May 27, 2018 8:51 PM
Last Updated: Sun, May 27, 2018 8:51 PM

Online URL: http://kb.ictbanking.net/article.php?id=70