SYNOPSISjfs_tune [options] device
jfs_tune adjusts tunable parameters on a Linux JFS file system or external journal. jfs_tune 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 or JFS external journal has been created.
- -J device=external-journal
- Attach the JFS external journal located on external-journal to the JFS file system on device.
- The external journal must already have been created using the command. More than one file system may share the same external journal.
- mkfs.jfs -J journal_dev external-journal
- Attach the external journal to the file system by using the command
- jfs_tune -J device=external-journal device
Instead of specifying a device name directly,
can also be specified by either
jfs_tune -l device
to display a journal device's volume label and UUID.)
List the contents of the JFS file system or external journal superblock
that resides on
- -L volume-label
Set the volume label of the JFS file system or external journal.
JFS labels can be at most 16 characters long; if
is longer than 16 characters,
will truncate it and print a warning. The volume label can be used
(and possibly others) by specifying
instead of a block special device name like
- -U UUID
Set the universally unique identifier (UUID) of the file system or
external journal device to
The format of the UUID is a series of hex digits separated by hyphens,
parameter may also be one of the following:
- clear the file system UUID
- generate a new randomly-generated UUID
- generate a new time-based UUID
- The UUID may be used by mount(8), fsck(8), and /etc/fstab(5) (and possibly others) by specifying UUID=uuid instead of a block special device name like /dev/hda1.
for more information.
Print version information and exit (regardless of any other chosen options).
Set a randomly-generated UUID for the JFS file system on the 3rd partition of the 2nd hard disk, and view the resultant superblock:
- jfs_tune -l -U random /dev/hdb3
Attach an already existing external journal on a device labeled JFSLog to a JFS file system on /dev/hda8:
- jfs_tune -J device=LABEL=JFSLog /dev/hda8
If you find a bug in JFS or jfs_tune, please report it via the bug tracking system ("Report Bugs" section) of the JFS project web site:
Please send as much pertinent information as possible including any error messages resulting from running jfs_tune.