Man page - jfs_tune(8)

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Manual

jfs_tune

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
REPORTING BUGS
SEE ALSO
AUTHOR

NAME

jfs_tune - adjust tunable file system parameters on JFS

SYNOPSIS

jfs_tune [options] device

DESCRIPTION

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.

OPTIONS

-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, 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 and UUID.)

-l

List the contents of the JFS file system or external journal superblock that resides on device .

-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 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 /dev/hda5 .

-U UUID

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 chosen options).

EXAMPLES

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

REPORTING BUGS

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:
http://jfs.sourceforge.net/

Please send as much pertinent information as possible including any error messages resulting from running jfs_tune .

AUTHOR

Barry Arndt (barndt@us.ibm.com)

jfs_tune is maintained by IBM.
See the JFS project web site for more details:
http://jfs.sourceforge.net/