---
name: "ffs"
section: "4"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/ffs/4"
---

# ffs(4)

Berkeley fast file system

## 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)](/fstab/5.md):

```
/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)](/quota/1.md) and [edquota(8)](/edquota/8.md).

### 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)](/newfs/8.md) command:

  **newfs** **-U** *fs*

  *fs* can be either a mount point listed in [fstab(5)](/fstab/5.md) (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)](/tunefs/8.md) command:

  **tunefs** **-n** **enable** *fs*

  Soft updates can also add journaling that reduces the time spent by [fsck\_ffs(8)](/fsck_ffs/8.md) 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)](/tunefs/8.md) command after [newfs(8)](/newfs/8.md) command with **-U** flag enabled. It is possible to enable soft updates journaling on an *unmounted* file system by using [tunefs(8)](/tunefs/8.md) command:

  **tunefs** **-j** **enable** *fs*

  This flag automatically enables the soft updates feature when it is not enabled. Note that this [tunefs(8)](/tunefs/8.md) 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)](/extattrctl/8.md).

- **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)](/gjournal/8.md) 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)](/newfs/8.md) 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)](/gjournal/8.md) utility to label the underlying block device and [tunefs(8)](/tunefs/8.md) utility to enable the block level journaling flag:

  **gjournal** **label** *da0*

  **tunefs** **-J** **enable** */dev/da0.journal*

  **mount** **-o** **async** */dev/da0.journal* */mnt*

### Xr sysctl 8 MIBs

The following [sysctl(8)](/sysctl/8.md) 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)](/quota/1.md), [acl(3)](/acl/3.md), [extattr(3)](/extattr/3.md), [edquota(8)](/edquota/8.md), [extattrctl(8)](/extattrctl/8.md), [fsck\_ffs(8)](/fsck_ffs/8.md), [sysctl(8)](/sysctl/8.md), [tunefs(8)](/tunefs/8.md) M. McKusick, W. Joy, S. Leffler, and R. Fabry, “A Fast File System for UNIX”, *ACM Transactions on Computer Systems*, 3, 2, 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.