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 com-
              mand

              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=vol-
              ume_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 cho-
              sen options).

EXAMPLES
       Set a randomly-generated UUID for the JFS file system on the 3rd parti-
       tion 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)
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