FFS(4)

NAME
ffs, ufs - 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).

vfs.ffs.prttimechgs
    Print a console message when timestamps for UFS1 filesystems are found to be in the future and are changed to be the present time. (Default: 0).

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, R. Fabry, August 1984, A Fast File System for UNIX, ACM Transactions on Computer Systems, 2, 3, 181-197. M. McKusick, June 2000, 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. M. McKusick, J. Roberson, May 2010, Journaled Soft-updates, BSD Canada Conference 2010 (BSDCan).