Ext4

Ext4 is a journaling filesystem for Linux and the successor to ext3. It supports large files, large volumes, and high file counts through features including extents and delayed allocation.

Extent: A contiguous range of filesystem blocks represented by a starting block and a length. Ext4 uses extents to represent file data in larger ranges than ext3’s block maps.
Inode: A filesystem record containing a file’s metadata and references to its data blocks. Ext4 stores file identity and metadata in inodes, separately from directory names.
Ext3: A Linux journaling filesystem that preceded ext4 and extended ext2 with a journal. Ext4 grew from ext3’s design while adding larger-scale storage support and new allocation features.
XFS: A high-performance journaling filesystem widely used on Linux systems, especially for large files and volumes. XFS is a common Linux alternative with different scalability and administration trade-offs.
Filesystem mount: The process of making a filesystem available at a directory in a system’s directory tree. Linux mounts ext4 volumes with options that can change behaviors such as access-time updates.
Journaling file system: A filesystem that records planned metadata changes in a log before applying them to its main structures. Ext4 journals metadata so it can restore filesystem consistency after an interrupted update.
Block group: A filesystem region that groups data blocks and related metadata for allocation and management. Ext4 organizes storage into block groups to keep related metadata and data relatively close.
Ext2: A Linux filesystem that stores files without an integrated journal. Ext2 is the earlier filesystem lineage from which ext3 and ext4 evolved.
Btrfs: A Linux copy-on-write filesystem with features such as snapshots, checksums, and multi-device management. Btrfs offers integrated snapshots and checksumming that ext4 does not provide.
e2fsprogs: A collection of Linux utilities for creating, checking, resizing, and tuning ext2, ext3, and ext4 filesystems. These utilities provide the standard tools for maintaining ext4 volumes.

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