FFS(7)             FreeBSD Miscellaneous Information Manual             FFS(7)

NAME
     ffs - Berkeley fast file system

SYNOPSIS
     In the kernel configuration file:
     options FFS
     options QUOTA
     options SOFTUPDATES
     options SUIDDIR
     options UFS_ACL
     options UFS_DIRHASH
     options UFS_EXTATTR
     options UFS_EXTATTR_AUTOSTART
     options UFS_GJOURNAL

     In fstab(5):
     /dev/disk0a     /mnt ufs rw 1 1

DESCRIPTION
     The Berkeley fast file system provides facilities to store file system
     data onto a disk device.  ffs has been optimized over the years for speed
     and reliability and is the default FreeBSD file system.

   Quotas
     options QUOTA
         This option allows system administrators to set limits on disk usage
         on a per-user basis.  Quotas can be used only on file systems mounted
         with the quota option; see quota(1) and edquota(8).

   Soft Updates
     options SOFTUPDATES
         The soft updates feature tracks writes to the disk and enforces
         metadata update dependencies (e.g., updating free block maps) to
         ensure that the file system remains consistent.

         To create a new file system with the soft updates enabled, use
         newfs(8) command:

               newfs -U fs

         fs can be either a mount point listed in fstab(5) (e.g., /usr), or a
         disk device (e.g., /dev/da0a).

         It is possible to enable soft updates on an unmounted file system by
         using tunefs(8) command:

               tunefs -n enable fs

         Soft updates can also add journaling that reduces the time spent by
         fsck_ffs(8) cleaning up a filesystem after a crash from several
         minutes to a few seconds.  The journal is placed in an inode named
         .sujournal, and is kept as a circular log of segments containing
         records that describe metadata operations.

         To create a new file system with both the soft updates and soft
         updates journaling enabled, use the following command:

               newfs -j fs

         This runs tunefs(8) command after newfs(8) command with -U flag
         enabled.  It is possible to enable soft updates journaling on an
         unmounted file system by using tunefs(8) command:

               tunefs -j enable fs

         This flag automatically enables the soft updates feature when it is
         not enabled.  Note that this tunefs(8) command will fail if a file
         .sujournal already exists before enabling the soft updates
         journaling.

   File Ownership Inheritance
     options SUIDDIR
         For use in file sharing environments on networks including Microsoft
         Windows and Apple Macintosh computers, this option allows files on
         file systems mounted with the suiddir option to inherit the ownership
         of its directory, i.e., "if it's my directory, it must be my file."

   Access Control Lists
     options UFS_ACL
         Access control lists allow the association of fine-grained
         discretionary access control information with files and directories.
         This option requires the presence of the UFS_EXTATTR option, and it
         is recommended that UFS_EXTATTR_AUTOSTART is included as well, so
         that ACLs are enabled atomically upon mounting the file system.

     In order to enable support for ACLs, two extended attributes must be
     available in the EXTATTR_NAMESPACE_SYSTEM namespace: posix1e.acl_access,
     which holds the access ACL, and posix1e.acl_default, which holds the
     default ACL for directories.  If you are using file system extended
     attributes, the following commands may be used to allocate space for and
     create the necessary EA backing files for ACLs in the root of each file
     system.  In these examples, the root file system is used; see Extended
     Attributes for more details.

           mkdir -p /.attribute/system
           cd /.attribute/system
           extattrctl initattr -p / 388 posix1e.acl_access
           extattrctl initattr -p / 388 posix1e.acl_default

     On the next mount of the root file system, the attributes will be
     automatically started if UFS_EXTATTR_AUTOSTART is included in the kernel
     configuration, and ACLs will be enabled.

   Directory Hashing
     options UFS_DIRHASH
         Implements a hash-based lookup scheme for directories in order to
         speed up accesses to very large directories.

   Extended Attributes
     options UFS_EXTATTR
         Extended attributes allow the association of additional arbitrary
         metadata with files and directories, which can be assigned and
         retrieved from userland as well as from within the kernel; see
         extattrctl(8).

     options UFS_EXTATTR_AUTOSTART
         If this option is defined, ffs will search for a .attribute
         subdirectory of the file system root during the mount operation.  If
         found, extended attribute support will be automatically started for
         that file system.

   GEOM-based Journaling
     options UFS_GJOURNAL
         Implements a block level journaling of a UFS file system, which is
         for both data and metadata.  To enable this, create a gjournal(8)
         GEOM provider for a block device by using the following command:

               gjournal label da0

         In this example, /dev/da0 is used as the target block device, and
         /dev/da0.journal is created.  Then create a new file system by using
         newfs(8) with the block level journaling flag and mount it:

               newfs -J /dev/da0.journal
               mount -o async /dev/da0.journal /mnt

         async option is not mandatory but recommended for better performance
         because the journaling guarantees the consistency of an async mount.

         It is also possible to enable the block level journaling on an
         existing file system.  To do so, use gjournal(8) utility to label the
         underlying block device and tunefs(8) utility to enable the block
         level journaling flag:

               gjournal label da0
               tunefs -J enable /dev/da0.journal
               mount -o async /dev/da0.journal /mnt

   sysctl(8) MIBs
     The following sysctl(8) MIBs are defined for use with ffs:

     vfs.ffs.doasyncfree       Asynchronously write out modified i-node and
                               indirect blocks upon reallocating file system
                               blocks to be contiguous.  (Default: 1).

     vfs.ffs.doreallocblks     Enable support for the rearrangement of blocks
                               to be contiguous.  (Default: 1).

HISTORY
     The ffs manual page first appeared in FreeBSD 4.5.

SEE ALSO
     quota(1), acl(3), extattr(3), edquota(8), extattrctl(8), fsck_ffs(8),
     sysctl(8), tunefs(8)

     M. McKusick, W. Joy, S. Leffler, and R. Fabry, "A Fast File System for
     UNIX", ACM Transactions on Computer Systems, 2, 3, 181-197, August 1984.

     M. McKusick, "Soft Updates: A Technique for Eliminating Most Synchronous
     Writes in the Fast Filesystem", Proceedings of the Freenix Track at the
     1999 Usenix Annual Technical Conference, 71-84, June 2000.

     M. McKusick and J. Roberson, "Journaled Soft-updates", BSD Canada
     Conference 2010 (BSDCan), May 2010.

FreeBSD 13.1-RELEASE-p6           May 3, 2020          FreeBSD 13.1-RELEASE-p6