manuals

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
              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
              command

              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)