FFS(5) BSD 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.
The following sysctl(8) MIBs are defined for use with ffs:
vfs.ffs.doasyncfree Asynchronously write out modified i-node and indi‐
rect 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.)
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 meta‐
data 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.
SEE ALSOquota(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.
BSD May 10, 2008 BSD
