The Berkeley fast file system
provides facilities to store file system data onto a disk device.
has been optimized over the years
for speed and reliability
and is the default
Fx file system.
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
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
file system, use the following command:
can be either a mount point listed in
or a disk device
File Ownership Inheritance
For use in file sharing environments
on networks including
this option allows files on file systems
mounted with the
to inherit the ownership of its directory,
``if it's my directory, it must be my file.''
Access Control Lists
Access control lists allow the association of
fine-grained discretionary access control information
with files and directories.
This option requires the presence of the
option, and it is recommended that
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
which holds the access ACL,
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;
Sx Extended Attributes
for more details.
On the next mount of the root file system,
the attributes will be automatically started
is included in the kernel configuration),
and ACLs will be enabled.
Implements a hash-based lookup scheme for directories
in order to speed up accesses to very large directories.
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
If this option is defined,
will search for a
subdirectory of the file system root during the mount operation.
If found, extended attribute support will be
automatically started for that file system.
MIBs are defined for use with
Asynchronously write out modified i-node and indirect blocks
upon reallocating file system blocks to be contiguous.
Enable support for the rearrangement of blocks
to be contiguous.