CentOS - Oct 2018 - "WARNING: fdisk GPT support is currently new"

Hi,

I'm currently teaching Linux system administration to a class at the
local "chambre de commerce". The course is based mainly on a minimal
CentOS 7 installation.

Usually my preferred tool for handling manual GPT partitioning is gdisk,
which is not installed on a minimal install. I just gave the good old
fdisk a spin, which enables GPT partition table creation with the 'g'
shortcut.

Here's what I get when listing a GPT-partitioned drive with fdisk:

# fdisk -l /dev/sdb
WARNING: fdisk GPT support is currently new, and therefore in an
experimental phase. Use at your own discretion.

Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
...

Now my first reaction would be to install gdisk (yum install gdisk) and
use this to handle GTP partitioning. But I'm curious. How
"experimental"
(e. g. prone to blow up in my face) is fdisk really? So far, I've only
used it for MBR-style partitioning.

Cheers from the sunny South of France,

Niki

-- 
Microlinux - Solutions informatiques durables
7, place de l'?glise - 30730 Montpezat
Site : https://www.microlinux.fr
Blog : https://blog.microlinux.fr
Mail : info at microlinux.fr
T?l. : 04 66 63 10 32

Le 07/10/2018 ? 12:09, Nicolas Kovacs a ?crit?:
> Now my first reaction would be to install gdisk (yum install gdisk) and
> use this to handle GTP partitioning. But I'm curious. How
"experimental"
> (e. g. prone to blow up in my face) is fdisk really? So far, I've only
> used it for MBR-style partitioning.
I have a follow-up remark.

Before CentOS, I've been using Slackware as my main OS on servers and
desktops. My policy for partitioning and formatting was always "Keep It
Simple", e. g. :

* use traditional fdisk with DOS-MBR style partitioning on systems that
supported it

* use GPT-style partitioning on systems that required it (like huge
drives or EFI systems)

As far as I can tell, the CentOS installer is doing something similar,
but "automagically". Please correct me if I'm wrong.

Cheers,

Niki

-- 
Microlinux - Solutions informatiques durables
7, place de l'?glise - 30730 Montpezat
Site : https://www.microlinux.fr
Blog : https://blog.microlinux.fr
Mail : info at microlinux.fr
T?l. : 04 66 63 10 32

On Oct 7, 2018, at 4:09 AM, Nicolas Kovacs <info at microlinux.fr>
wrote:
> 
> How "experimental"
> (e. g. prone to blow up in my face) is fdisk really? So far, I've only
> used it for MBR-style partitioning.
I have no idea.  In fact, before your post, I had no idea fdisk even had GPT
awareness.

I?m replying because you have a third option besides fdisk and gdisk, which
should be present on a minimal install, and which is extremely well-tested for
the GPT case: parted.

On Oct 7, 2018, at 4:49 AM, Nicolas Kovacs <info at microlinux.fr>
wrote:
> 
> * use traditional fdisk with DOS-MBR style partitioning on systems that
> supported it
Unless you only need 4 or fewer partitions and are using 2TB or smaller disks, I
can?t see any good reason to use MBR on desktop, laptop, or server systems these
days.

(MBR does still have some well-justified use in the embedded world, removable
media, etc.)
> As far as I can tell, the CentOS installer is doing something similar,
> but "automagically". Please correct me if I'm wrong.
I believe the primary criteria the CentOS installer uses is that it checks
whether it was booted via EFI or BIOS.  If EFI, it assumes it must use GPT
partitioning to get a bootable system.

Obviously if you?re installing onto a > 2TB disk or drive array, it also uses
GPT.

You can tell which case you?ve fallen into by doing manual partitioning in the
installer and then seeing whether the installer offers you the option of
creating a ?biosboot? partition or /boot/efi.

On 10/07/2018 03:09 AM, Nicolas Kovacs wrote:
> use this to handle GTP partitioning. But I'm curious. How
"experimental"
> (e. g. prone to blow up in my face) is fdisk really? So far, I've only
> used it for MBR-style partitioning.
I always use fdisk for CentOS 7 and do manual partitioning, because I 
align all partition at 4 MiB (in order to align them to SSD/NVMe's erase 
block size). All my CentOS machines have GPT. Haven't seen any issues so 
far.

Not trying to prove anything. That's just my personal experience.

-- 
Yan Li