jfs_mkfs

jfs_mkfs [-q] [-v] [-F] [-f] [-s size] [-n aggregate-name] [-m mount-point] [-M multi-device] [-J size=number] [-A yes|no] [-L volume-label] [-P fs-uuid] [-o option] [-V] device

-A yes|no
    Enable (yes) or disable (no) inline log allocation

-F
    Force creation without interactive prompt

-f
    Force on potentially mounted or in-use device

-J size[=number]
    Size of external journal in aggregates (default 16MB)

-L volume-label
    Set volume label (max 128 chars)

-m mount-point
    Set default mount point

-M multi-device
    Multi-device filesystem (device name)

-n aggregate-name
    Set filesystem aggregate name (max 16 chars)

-o option
    Filesystem options like AGGRSIZE=nnn, NOINODEBTL=0|1

-P fs-uuid
    Set filesystem UUID

-q
    Quiet mode, suppress non-error messages

-s size
    Filesystem size in MB (default: whole device)

-v
    Verbose mode

-V
    Display version information

jfs_mkfs is a utility from the JFSUtils package used to format a block device with a Journaled File System (JFS). JFS, developed by IBM, is a high-performance, scalable 64-bit filesystem supporting large volumes (up to 32 TiB), files (up to 8 EiB), extents, dynamic inodes, compression, and online defragmentation. It uses journaling for data integrity.

Invoke as root to create a filesystem, typically on a partition like /dev/sdb1. The command detects the device's size by default but allows specifying with -s. It prompts for confirmation to prevent accidental data loss unless overridden with -F or -f. Post-creation, verify with jfs_fsck, then mount via mount -t jfs.

JFS is robust for enterprise use but unmaintained in modern Linux kernels (still compilable). Requires JFS kernel module. Always back up data before use, as it erases the entire target device.

Destroys all data on target device; requires root privileges; JFS unmaintained in Linux kernels since ~2017; test with jfs_fsck before mounting.

jfs_mkfs -q -A yes /dev/sdb1
Creates quiet JFS with inline logs on /dev/sdb1.

Internal journal default; use -J for external on separate device for large filesystems.

Developed by IBM for AIX/OS/2 (1990s); Linux port by IBM/Steve Best in 2001; integrated into kernel 2.4.x; marked unmaintained post-2011.

mkfs(8), jfs_fsck(8), jfs_tune(8), mount(8)