Modern boot firmware, partition table, and file systems

최초 작성일: 2022년 08월 18일
최근 수정일: 2022년 08월 19일

Overview

This post compares BIOS/UEFI, MBR/GPT, and different file systems such as NTSF/APFS/EXT4/XFS/exFAT.

Description

Boot firmware: BIOS vs UEFI

Boot firmware	BIOS	UEFI

A boot firmware is stored in the motherboard; this firmware initializes the system devices, and then runs the boot loader that loads the installed OS. This firmware is known as the BIOS (Basic Input/Output System) or UEFI (Unified Extensible Firmware Interface).

Boot stages

• System startup
  • identifies, tests, and initializes system devices (e.g., CPU)
• Boot
  • locates boot loader on boot deivces (e.g., HDD, USB, CD, etc.)
  • transfers control to the loaded sector
  • the boot program from the boot sector interprets the partition table
  • loads installed OS

BIOS and UEFI are not the same, but both do the same job; UEFI replaces the legacy BIOS. (More info, More info2)

Partition table: MBR vs. GPT

Partition Table	MBR	GPT

First accessed on one of the boot processes of BIOS/UEFI when "the boot program from the boot sector interprets the partition table."

Source, Source2

Reasons for MBR partition table:

• if you have an old system with BIOS
  • the legacy BIOS is unable to boot off of GPT-partitioned disks

Reasons for GPT partition table:

• if you have a modern system with UEFI
  • UEFI requires GPT on the system’s boot drive
• if the drive is larger than 2TB

Differences:

Partition Table	MBR	GPT
# of partitions	max. 4	max. 128
max. storage	2.2 TB	9.4ZB

File system format: boot and data

	EXT4	XFS	APFS	NTFS	exFAT
Linux	boot/data	boot/data	x1	x1	data
macOS	x2	x2	boot/data	read-only2	data
Windows	x3	x3	x3	boot/data	data

compatibility

RHEL

https://access.redhat.com/articles/rhel-limits#file-systems-and-storage-limits-5 https://access.redhat.com/articles/3129891

• EXT4
• XFS
• BtrFS
  • It was fully removed in Red Hat Enterprise Linux 8.⁴

macOS

• APFS
  • default for macOS 11 and later
• HFS+
  • default for macOS 10.15 and earlier

Windows

• NTFS
• FAT32
  • 4GB size limit for single files

Label format

	Linux	macOS	Windows
Boot
Data	LVM		msftdata

Solution

How to convert partition tables, format file systems, and manage partitions will be covered in a separate post.

References

• https://access.redhat.com/solutions/3781221

1. mount APFS, NTFS on Linux ↩

2. mount EXT4/XFS, NTFS on macOS ↩

3. mount EXT4/XFS, APFS on Windows ↩

4. “Will Btrfs be supported on Red Hat Enterprise Linux?”, Red Hat ↩