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
I -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
R 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
I jfs_tune -J device=external-journal
device
Instead of specifying a device name directly,
external-journal
can also be specified by either
I LABEL= label
or
I UUID= UUID
(Use
I 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
R device .
I -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
I LABEL= volume_label
instead of a block special device name like
R /dev/hda5 .
I -U UUID
Set the universally unique identifier (UUID) of the file system or
external journal device to
R 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
I UUID= uuid
instead of a block special device name like
R /dev/hda1 .
See
uuidgen(8)
for more information.
I -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
R 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
R jfs_tune .
SEE ALSO
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/
