filesystems.md

Filesystems

Btrfs

• btrfs -v filesystem defrag -r -czstd / = Recursively compress filesystem with zstd.

Ext4

• mkfs.ext4 /dev/mapper/LV1 or mkfs -t ext4 /dev/mapper/LV1 = Create ext4 filesystem on logical volume LV1.
  
  
• e2fsck -f /dev/mapper/LV1 && resize2fs /dev/mapper/LV1 = Expand filesystem to fit size of LV1 (must be unmounted).
• e4degrag / = Defragment all partitions.
• fsck /dev/sda2 = Check sda2 for errors.

XFS

• xfs_growfs /dev/centos/var = Expand mounted XFS filesystem (must be mounted).

NOTE: XFS filesystems cannot be shrunk.

Ext4 vs XFS

• ext4 is faster on single-threaded IO and when working with many small files.
• XFS is faster on multi-threaded IO, performs better with large files (>100MB).

Filesystem features 1	ext4	XFS	Btrfs	ZFS	UFS2	F2FS	NTFS	bcachefs	FAT32	exFAT
Online/offline growing	yes	online	yes	online	yes	offline	yes	?	no	no
Online/offline shrinking	offline	no	yes	no	no	no	yes	?	no	no
Transparent compression	no	no	yes	yes	?	yes	yes	yes	no	no
Encryption	LUKS	LUKS	yes	yes	?	yes	yes	yes	no	no
Data deduplication	no	no	yes	yes	no	no	yes	yes	no	no
Snapshots	LVM	LVM	yes	yes	?	no	no	yes	no	no
Block + metadata checksums	no	no	yes	yes	no	no	no	yes	no	no
Block + metadata journaling	yes	yes	CoW	CoW	metadata	CoW	metadata	CoW	no	no
Built-in RAID support	LVM	LVM	yes	yes	no	?	yes	yes	no	no
File change log	no	yes	no	no	no	no	yes	no	no	no
Maximum file size	-	-	-	-	-	-	-	-	4GB	-

• LUKS = Encrypting these filesystems is usually handled through LUKS and/or dm-crypt.
• LVM = This feature is traditionally provided through LVM.
• CoW = Journaling is superceded by copy-on-write mechanisms.
• - = Maximum theoretical size is large enough to be irrelevant.
• ? = Currently unknown and/or no reliable data available.