DragonFly On-Line Manual Pages

FFS(5)                   DragonFly File Formats Manual                  FFS(5)

NAME
     ffs, ufs - Berkeley fast file system

SYNOPSIS
     In the kernel configuration file:
     options FFS
     options QUOTA
     options SOFTUPDATES
     options SUIDDIR
     options UFS_DIRHASH

     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 DragonFly file system for /boot.

   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 enable soft updates on an unmounted file system, use the following
         command:

               tunefs -n enable fs

         fs can be either a mount point listed in fstab(5) (e.g., /usr), or a
         disk device (e.g., /dev/da0s0a).

   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."

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

SYSCTL VARIABLES
     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.)

     vfs.ufs.dirhash_docheck      Enable extra sanity tests.  (Default: 0.)

     vfs.ufs.dirhash_mem          Current dirhash memory usage.

     vfs.ufs.dirhash_maxmem       Maximum allowed dirhash memory usage.

     vfs.ufs.dirhash_minsize      Minimum directory size in bytes for which to
                                  use hashed lookup.

SEE ALSO
     quota(1), edquota(8), sysctl(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.

DragonFly 6.1-DEVELOPMENT      February 17, 2018     DragonFly 6.1-DEVELOPMENT