---
name: "jfs_mkfs"
section: "8"
platform: "linux"
package: "jfsutils"
version: "1.1.15-9"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/jfs_mkfs"
---

# jfs\_mkfs(8)

create a JFS formatted partition

## NAME

**jfs\_mkfs** - create a JFS formatted partition

## SYNOPSIS

**jfs\_mkfs** \[options\] *device* \[ blocks \]

## DESCRIPTION

**jfs\_mkfs** is used to create (format) a JFS partition. **jfs\_mkfs** must be run as root.

*device* is the special file name corresponding to the actual device (e.g. */dev/hdb1*) on which a JFS file system and/or JFS journal will be created. *blocks* is the number of blocks to be used for the file system.  If omitted, **jfs\_mkfs** automatically figures the file system size.

The default block size is **4096**.

## WARNING

**jfs\_mkfs** will destroy all data on the specified device!

## OPTIONS

- **-c**

  Check the device for bad blocks before building the file system.

- **-j** *journal\_device*

  Create the external JFS journal on *journal\_device* , create the JFS file system on *device* , and attach the external journal to the file system.

- **-J** *journal-options*

  Create the JFS journal on its own device or attach an external JFS journal to the JFS file system using options specified on the command-line. The following journal options are supported:

  - **journal\_dev**

    Create an external JFS journal on the given device.

  - **device=***external-journal*

    Attach an existing external JFS journal located on *external-journal* to the JFS file system that will be created on *device*. The external journal must already have been created using the command

  -

    **jfs\_mkfs -J journal\_dev** *external-journal*

  -

    Attach the external journal to the file system being created by using the command

  -

    **jfs\_mkfs -J device=***external-journal* *device*

  -

    Instead of specifying a device name directly, *external-journal* can also be specified by either **LABEL=***label* or **UUID=***UUID* to locate the external journal by either the volume label or UUID stored in the JFS external log superblock at the start of the journal.  Use [**jfs\_tune**(8)](/jfs_tune/8.md) to display a journal device's volume label and UUID.  (See the **-l**, **-L**, and **-U** options of [**jfs\_tune**(8)](/jfs_tune/8.md).)

-

  Only one of the **journal\_dev** or **device=** options can be given per **jfs\_mkfs** issuance.

- **-L** *volume\_label*

  Set the volume label for the newly formatted device.

-

  If **-L** *volume\_label* is used along with **-J journal\_device**, the volume label of the specified external journal device will be set to *volume\_label*. Otherwise, the volume label of the JFS file system will be set to *volume\_label*.

- **-O**

  Provide case-insensitive support for compatibility with OS/2.

- **-q**

  Quiet execution - do not ask for confirmation before creating the file system.

- **-s** *log\_size*

  Set the log size (in megabytes) of the inline log.  If the **-s** option is not used, the default log size is 0.4% of the aggregate size.

- **-V**

  Print version information and exit (regardless of any other chosen options).

## EXAMPLES

Format 3rd partition on 2nd hard disk with the volume label "JFS\_hdb3":

-

  **jfs\_mkfs -L JFS\_hdb3 /dev/hdb3**

-

  Format 5th partition on 1st hard disk, verifying each block created:

-

  **jfs\_mkfs -c /dev/hda5**

-

  Format 3rd partition on 2nd hard disk as external journal, format 4th partition on 1st hard disk as JFS file system, and attach the external journal to the file system:

-

  **jfs\_mkfs -j /dev/hdb3 /dev/hda4**

-

  ## REPORTING BUGS

If you find a bug in **JFS** or **jfs\_mkfs**, please report it via the bug tracking system ("Report Bugs" section) of the JFS project web site:

```
http://jfs.sourceforge.net/
```

Please send as much pertinent information as possible including any error messages resulting from running **jfs\_mkfs**.

## SEE ALSO

[**mkfs**(8)](/mkfs/8.md)**,** [**jfs\_fsck**(8)](/jfs_fsck/8.md)**,** [**jfs\_fscklog**(8)](/jfs_fscklog/8.md)**,** [**jfs\_tune**(8)](/jfs_tune/8.md)**,** [**jfs\_logdump**(8)](/jfs_logdump/8.md)**,** [**jfs\_debugfs**(8)](/jfs_debugfs/8.md)

## AUTHORS

```
Barry Arndt  (barndt@us.ibm.com)
William Braswell, Jr.
```

**jfs\_mkfs** is maintained by IBM.

```
See the JFS project web site for more details:
http://jfs.sourceforge.net/
```