jfs_tune

jfs_tune(8)             Set JFS file system parameters.            jfs_tune(8)



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.


SEE ALSO
       jfs_fsck(8), jfs_mkfs(8), jfs_fscklog(8), jfs_logdump(8),
       jfs_debugfs(8)



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/



                               October 28, 2002                    jfs_tune(8)