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Disk Types in Linux

You can view disks in Linux with fdisk -l.

Disks can have different names depending on the type of storage device, and the kernel driver that's managing the storage device.

Disk and Partition Naming Conventions

The name of a disk on your system can tell you what type of disk it is, and if it's a partition or not.
Disk names will named with this format: 

[prefix][a-z][number]
e.g.:
xvda
xvda1

  • xvd is the prefix
  • a is the position of the disk
  • 1 is the number of the partition. If there's no number, it's not a partition.

Different Types of Disks and their Names (Prefixes)

  • /dev/sd*: The sd prefix stands for "SCSI Disk".

    • Historically used for ONLY SCSI drives, but now it's also used for most modern storage devices (i.e., SATA and USB drives) because they're managed by the same kernel driver (sd driver).

  • /dev/xvd*: The xvd prefix stands for "eXtended Virtual Disk" (or Xen Virtual Disk).

    • This is used primarily in Xen-based virtual machines.
    • In cloud environments like AWS, xvd* names are used to identify virual disks.

  • /dev/nvme*: The nvme prefix stands for "Non-Volatile Memory Express".

    • This is used for NVMe SSDs, which are high-performance SSDs connected via the PCIe bus.
    • NVMe drives have a different naming convention, more similar to network interfaces.
      • e.g., nvme0n1: nvme0 refers to the controller, n1 refers to the namespace or disk on that controller.

Types of File Systems

There are many types of file systems, or "disk formats." Each one has their own pros and cons, and their own use cases.

Standard File System Types

  • ext4: Fourth Extended File System

    • Used for many Linux distributions.
    • Generally only compatible with Linux, though some tools can read these file systems on other OSs.
    • Best for Linux systems that need stability, performance, and large file support.

  • nfs: Network File System

    • A network-based file system protocol that allows user to access files over a network, as if they were on the local system.
    • Great for environments that need to share files across multiple systems over the network.

  • FAT32: File Allocation Table 32

    • An older file system that is widely compatible across operating systems.
    • Maximum file size on FAT32 file systems is 4GB.
    • Best for smaller storage devices or drives that need to be compatible with different operating systems.

  • exFAT: Extended File Allocation Table

    • Designed as a replacement for FAT32, mainly for flash drives and larger external storage devices.
    • Support large files (no 4GB limit like FAT32).
    • Compatible with Windows and macOS, but less compatible than FAT32 (especially with older systems).
    • Best for large external drives or flash drives that need to handle files over 4GB.

  • NTFS: New Technology File System

    • Mainly used by Windows operating systems.
    • Supports large files and volumes.
    • Has journaling, file permissions, encryption, and compression options.
    • Only compatible with Windows, but has read-only access on Linux and MacOS.

  • APFS: Apple File System

    • This is Apple's default file system for macOS, iOS, and other Apple devices.
    • Designed for flash storage
    • Supports encryption, cloning, snapshots, and space sharing.
    • Only compatible with Apple devices.

More Advanced File System Types

  • ZFS: Zettabyte File System

    • Used on Linux, FreeBSD, and Solaris.
    • Has high data integrity, native RAID, snapshots, deduplication, and self-healing.
    • Great in enterprise servers, high-reliability storage environments, data backups, and cloud storage systems.

  • Btrfs: B-Tree File System

    • Used on Linux.
    • Supports snapshots, subvolumes, pooling, compression, and self-healing.
    • Best for Linux systems with complex storage needs, virtualization, and high-availability environments.

  • XFS: eXtended File system

    • Used on Linux.
    • Supports large files and volumes.
    • High performance with parallel I/O, and efficient metadata handling.
    • Used for enterprise environments, databases, large files, and workloads taht require fast data access.

  • HFS+: Hierarchical File System Plus

    • Used on older macOS versions.
    • Supports journaling, unicode support, and backward compatibility with HFS.
    • Only compatible with macOS.

Specialized and Networked File System Types

  • ISO 9660

    • Used for CD-ROMs and DVDs.
    • Only supports read-only access.
    • Used for CDs, DVDs, bootable media, and software distribution.

  • SMB: Server Message Block

    • Network-based file system usable by Windows/Linux/macOS.
    • Allows shared access to files, prointers, and serial ports over a network.
    • Typically used by Windows for file sharing.
    • Used for file sharing over a network in Windows environments and NAS.

  • CIFS: Common Internet File System

    • Network-based, cross-platform file system.
    • A version of SMB for network file sharing.
    • Compatible with Windows, Linux, and macOS.
    • Legacy file system. Used for Windows file sharing, NAS, and simple cross-platform file access.

  • HDFS: Hadoop Distributed File System

    • Distributed file system, Linux-based.
    • Supports distributed storage and parallel processing, designed for fault tolerance and scalability.
    • Used in big data applications and distributed data processing in Hadoop clusters.

  • tmpfs: Temporary File System

    • Used on Linux/Unix systems.
    • Creates a temporary file system in memory.
    • Data is lost on shutdown or reboot.
    • Great for fast-access cache and temporary file storage for files that don't need to persist between reboots.