jfs_tune - adjust tunable file system parameters on JFS
jfs_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
Only supported on JFS versions (1.0.18 or later) that support
external journal. Attach the JFS external journal located on
external-journal to the JFS file system on device.
Currently, you may only attach a single JFS file system device
to a single JFS external journal (i.e. each JFS file system
using an external journal must have a unique external journal).
The external journal must already have been created using the
mkfs.jfs -J journal_dev external-journal
Attach the external journal to the file system by using the
jfs_tune -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 (Use
jfs_tune -l device to display a journal device’s volume label
-l List the contents of the JFS file system or external journal
superblock that resides on device.
Set the volume label of the JFS file system or external journal.
JFS labels can be at most 16 characters long; if volume-label is
longer than 16 characters, jfs_tune will truncate it and print a
warning. The volume label can be used by mount(8), fsck(8), and
/etc/fstab(5) (and possibly others) by specifying
LABEL=volume_label instead of a block special device name like
Set the universally unique identifier (UUID) of the file system
or external journal device to UUID. The format of the UUID is a
series of hex digits separated by hyphens, like this:
"c1b9d5a2-f162-11cf-9ece-0020afc76f16". The UUID parameter may
also be one of the following:
clear clear the file system UUID
random generate a new randomly-generated UUID
time 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.
See uuidgen(8) for more information.
-V Print version information and exit (regardless of any other
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.
jfs_fsck(8), jfs_mkfs(8), jfs_fscklog(8), jfs_logdump(8),
Barry Arndt (email@example.com)
jfs_tune is maintained by IBM.
See the JFS project web site for more details:
October 28, 2002 jfs_tune(8)