# JFS file system interface module

The JFS FSIM lets EVMS users create and manage JFS file systems from within the EVMS interfaces. In order to use the JFS FSIM, version 1.0.9 or later of the JFS utilities must be installed on your system. The latest version of JFS can be found at http://oss.software.ibm.com/jfs/.

## Creating JFS file systems

JFS file systems can be created with `mkfs` on any EVMS or compatibility volume (at least 16 MB in size) that does not already have a file system. The following options are available for creating JFS file systems:

badblocks

  Perform a read-only check for bad blocks on the volume before creating the file system. The default is false.

caseinsensitive

  Mark the file system as case-insensitive (for OS/2 compatibility). The default is false.

vollabel

  Specify a volume label for the file system. The default is none.

journalvol

  Specify the volume to use for an external journal. This option is only available with version 1.0.20 or later of the JFS utilities. The default is none.

logsize

  Specify the inline log size (in MB). This option is only available if the journalvol option is not set. The default is 0.4% of the size of the volume up to 32 MB.

## Checking JFS file systems

The following options are available for checking JFS file systems with `fsck`:

force

  Force a complete file system check, even if the file system is already marked clean. The default is false.

readonly

  Check the file system is in read-only mode. Report but do not fix errors. If the file system is mounted, this option is automatically selected. The default is false.

omitlog

  Omit replaying the transaction log. This option should only be specified if the log is corrupt. The default is false.

verbose

  Display details and debugging information during the check. The default is false.

version

  Display the version of `fsck.jfs` and exit without checking the file system. The default is false.

## Removing JFS file systems

A JFS file system can be removed from its volume if the file system is unmounted. This operation involves erasing the superblock from the volume so the file system will not be recognized in the future. There are no options available for removing file systems.

## Expanding JFS file systems

A JFS file system is automatically expanded when its volume is expanded. However, JFS only allows the volume to be expanded if it is mounted, because JFS performs all of its expansions online. In addition, JFS only allows expansions if version 1.0.21 or later of the JFS utilities are installed.

## Shrinking JFS file systems

At this time, JFS does not support shrinking its file systems. Hence, volumes with JFS file systems cannot be shrunk.