jfs_mkfs

jfs_mkfs [-b blocksize] [-i inodesize] [-l logsize] [-o options] [-V] device

-b blocksize
    Specifies the block size for the JFS file system. blocksize must be a power of 2 between 512 and 32768 bytes. Default is 4096 bytes.

-i inodesize
    Specifies the inode size for the JFS file system. inodesize must be a power of 2 between 256 and 4096 bytes. Default is 256 bytes.

-l logsize
    Specifies the log size (journal size) for the JFS file system in megabytes. Default is 4MB.

-o options
    Specifies additional options for the JFS file system. This is a comma-separated list of options. Valid options include: agsize=size (allocation group size), nrfiles=number (number of files), sectorsize=size (sector size). The usage of options varies among different Linux distributions.

-V
    Prints the version information of the jfs_mkfs utility and exits.

device
    The device (e.g., /dev/sda1) or file to be formatted as a JFS file system. This is a required parameter.

The jfs_mkfs command is used to create a new JFS (Journaled File System) file system on a specified device or partition. It formats the device according to the JFS structure, initializing the necessary metadata and data structures for the file system to operate correctly.
Using this command is crucial before mounting a new JFS partition or after completely wiping an existing one. Incorrect usage can lead to data loss, so careful attention should be paid to the specified device and options. jfs_mkfs handles important aspects like allocating inodes, initializing the superblock, and setting up the journal area, ensuring the file system's integrity and reliability. The user should ensure they are using the correct options to optimize performance. For example, setting the blocksize according to the expected predominant filesize.
The jfs_mkfs command only supports the creation of JFS filesystems; it cannot be used to manage or modify existing filesystems.

Creating a JFS filesystem with jfs_mkfs will destroy all data on the specified device or file. Ensure you have backed up any important data before running this command. The command must be run as root or with sufficient privileges.

If jfs_mkfs encounters errors during the creation process (e.g., invalid parameters, insufficient disk space), it will typically exit with a non-zero status code. Check the standard error output for more information.

After creating the JFS filesystem, it's advisable to run fsck.jfs on the newly created filesystem to ensure its consistency. This is particularly important if the creation process was interrupted.

JFS was initially developed by IBM and later ported to Linux. jfs_mkfs, the utility to create JFS filesystems, was developed alongside the kernel driver to facilitate the adoption of JFS on Linux systems. JFS was designed to be a high-performance, scalable, and reliable filesystem, suitable for both server and desktop environments.

mount(8), umount(8), fsck.jfs(8), mkfs(8)