Sysadmin Linux Theory

File_System_Types

Detailed exploration of different Linux filesystem types including ext4, XFS, Btrfs, and their characteristics

File system types define how data is organized, stored, and accessed on storage devices in Linux. Understanding different file systems is crucial for system administration, as each type offers unique features for performance, reliability, and specific use cases.

Key Concepts

  • File System: Structure that organizes data on storage
  • Journaling: Tracks changes before writing to disk
  • Mounting: Making file systems accessible in directory tree
  • Inode: Data structure storing file metadata
  • Block Size: Minimum storage allocation unit
  • Extent: Contiguous group of blocks

Command Syntax

mkfs.type [options] device

  • Create file system on device
  • Type specifies file system format

mount -t type device mountpoint

  • Mount file system at specified location

Common File System Types

ext4 (Fourth Extended File System)

  • Default on most Linux distributions
  • Journaling, large file support (16TB)
  • Backward compatible with ext2/ext3

XFS

  • High-performance journaling file system
  • Excellent for large files and parallel I/O
  • Default on Red Hat Enterprise Linux

Btrfs (B-tree File System)

  • Copy-on-write, snapshots, compression
  • Built-in RAID support
  • Still considered experimental for production

ZFS

  • Advanced features: snapshots, deduplication
  • Integrated volume management
  • Requires additional installation on most distros

NTFS

  • Windows file system
  • Read/write support via ntfs-3g package

FAT32/exFAT

  • Cross-platform compatibility
  • Limited file size (4GB max for FAT32)

Practical Examples

Example 1: Check current file systems 

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df -T
Filesystem     Type     1K-blocks    Used Available Use% Mounted on
/dev/sda1      ext4      20642428 5123456  14567890  26% /
/dev/sda2      xfs       52428800 1234567  51194233   3% /home

Shows mounted file systems and their types

Example 2: Create ext4 file system 

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sudo mkfs.ext4 /dev/sdb1
mke2fs 1.45.5 (07-Jan-2020)
Creating filesystem with 2621440 4k blocks

Formats partition with ext4 file system

Example 3: Mount with specific type 

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sudo mount -t xfs /dev/sdc1 /mnt/data

Explicitly specifies XFS file system type

Example 4: View file system info 

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sudo blkid /dev/sda1
/dev/sda1: UUID="a1b2c3d4-e5f6-7890-abcd-ef1234567890" 
TYPE="ext4" PARTUUID="12345678-01"

Shows file system type and UUID

Use Cases

ext4

  • General purpose Linux installations
  • Desktop and server environments
  • Good balance of features and stability

XFS

  • Large file storage (media, databases)
  • High-performance computing
  • Systems requiring parallel I/O

Btrfs

  • Development environments
  • Systems needing snapshots
  • Advanced storage features testing

NTFS/FAT32

  • Dual-boot systems with Windows
  • External drives for cross-platform use
  • USB flash drives

lsblk -f - List block devices with file systems fsck - File system check and repair tune2fs - Adjust ext2/3/4 parameters xfs_info - Display XFS file system info findmnt - Find mounted file systems

Tips & Troubleshooting

Performance Considerations

  • XFS better for large files, ext4 for small files
  • Consider block size for your workload
  • SSD vs HDD affects file system choice

Common Issues

  • Mount fails: Check file system type with blkid
  • Corruption: Use appropriate fsck command
  • Full disk: Different file systems handle this differently

Best Practices

  • Always unmount before fsck operations
  • Keep file system drivers updated
  • Test new file systems in non-production first
  • Consider backup strategy with file system features

Security Notes

  • Some file systems support encryption (ext4, Btrfs)
  • File permissions work differently across types
  • NTFS ACLs may not translate to Linux permissions