mount_ufs - mount ufs file systems
mount -F ufs [generic_options] [-o specific_options] [-O]
special | mount_point
mount -F ufs [generic_options] [-o specific_options] [-O]
The mount utility attaches a ufs file system to the file
system hierarchy at the mount_point, which is the pathname
of a directory. If mount_point has any contents prior to the
mount operation, these are hidden until the file system is
If mount is invoked with special or mount_point as the only
arguments, mount will search /etc/vfstab to fill in the
missing arguments, including the specific_options. See
If special and mount_point are specified without any
specific_options, the default is rw.
If the directory on which a file system is to be mounted is
a symbolic link, the file system is mounted on the directory
to which the symbolic link refers, rather than on top of the
symbolic link itself.
See mount(1M) for the list of supported generic_options.
The following options are supported:
Specify ufs file system specific options in a
comma-separated list with no intervening spaces.
If invalid options are specified, a warning mes-
sage is printed and the invalid options are
ignored. The following options are available:
dfratime | nodfratime
By default, writing access time updates to
the disk may be deferred (dfratime) for the
file system until the disk is accessed for
a reason other than updating access times.
nodfratime disables this behavior.
If power management is enabled on the sys-
tem, do not set nodfratime unless noatime
is also set. If you set nodfratime without
setting noatime, the disk is spun up every
time a file within a file system on the
disk is accessed - even if the file is not
forcedirectio | noforcedirectio
If forcedirectio is specified and supported
by the file system, then for the duration
of the mount, forced direct I/O will be
used. If the filesystem is mounted using
forcedirectio, data is transferred directly
between user address space and the disk. If
the filesystem is mounted using nofor-
cedirectio, data is buffered in kernel
address space when data is transferred
between user address space and the disk.
forcedirectio is a performance option that
is of benefit only in large sequential data
transfers. The default behavior is nofor-
global | noglobal
If global is specified and supported on the
file system, and the system in question is
part of a cluster, the file system will be
globally visible on all nodes of the clus-
ter. If noglobal is specified, the mount
will not be globally visible. The default
behavior is noglobal. The global option is
mutually exclusive of the nbmand option,
intr | nointr
Allow (do not allow) keyboard interrupts to
kill a process that is waiting for an
operation on a locked file system. The
default is intr.
largefiles | nolargefiles
If nolargefiles is specified and supported
by the file system, then for the duration
of the mount it is guaranteed that all reg-
ular files in the file system have a size
that will fit in the smallest object of
type off_t supported by the system perform-
ing the mount. The mount will fail if there
are any files in the file system not meet-
ing this criterion. If largefiles is speci-
fied, there is no such guarantee. The
default behavior is largefiles.
If nolargefiles is specified, mount will
fail for ufs if the file system to be
mounted has contained a large file (a file
whose size is greater than or equal to 2
Gbyte) since the last invocation of fsck on
the file system. The large file need not
be present in the file system at the time
of the mount for the mount to fail; it
could have been created previously and des-
troyed. Invoking fsck (see fsck_ufs(1M)) on
the file system will reset the file system
state if no large files are present. After
invoking fsck, a successful mount of the
file system with nolargefiles specified
indicates the absence of large files in the
file system; an unsuccessful mount attempt
indicates the presence of at least one
logging | nologging
If logging is specified, then logging is
enabled for the duration of the mounted
file system. Logging is the process of
storing transactions (changes that make up
a complete UFS operation) in a log before
the transactions are applied to the file
system. Once a transaction is stored, the
transaction can be applied to the file sys-
tem later. This prevents file systems from
becoming inconsistent, therefore eliminat-
ing the need to run fsck. And, because
fsck can be bypassed, logging reduces the
time required to reboot a system if it
crashes, or after an unclean halt.
The default behavior is logging for all UFS
The log is allocated from free blocks in
the file system, and is sized approximately
1 Mbyte per 1 Gbyte of file system, up to a
maximum of 64 Mbytes.
Logging is enabled on any UFS file system,
including root (/), except under the fol-
o When logging is specifically dis-
o If there is insufficient file system
space for the log. In this case, the
following message is displayed and
file system is still mounted:
# mount /dev/dsk/c0t4d0s0 /mnt
/mnt: No space left on device
Could not enable logging for /mnt on /dev/dsk/c0t4d0s0.
The log created by UFS logging is
continually flushed as it fills up.
The log is totally flushed when the
file system is unmounted or as a
result of the lockfs -f command.
m Mount the file system without making an
entry in /etc/mnttab.
nbmand | nonbmand
This option specifies that non-blocking
mandatory locking semantics should be
allowed on this file system. Non-blocking
mandatory locking is disallowed by default.
If the file system is mounted with the
nbmand option, then applications can use
the fcntl(2) interface to place non-
blocking mandatory locks on files and the
system will enforce those semantics. Ena-
bling this option can cause standards con-
formant applications to see unexpected
Do not use the nbmand option with /, /var
The remount option should not be used to
change the nbmand disposition of the file
system. The nbmand option is mutually
exclusive of the global option, described
By default, the file system is mounted with
normal access time (atime) recording. If
noatime is specified, the file system will
ignore access time updates on files, except
when they coincide with updates to the
ctime or mtime. See stat(2). This option
reduces disk activity on file systems where
access times are unimportant (for example,
a Usenet news spool).
noatime turns off access time recording
regardless of dfratime or nodfratime.
The POSIX standard requires that access
times be marked on files. -noatime ignores
them unless the file is also modified.
onerror = action
This option specifies the action that UFS
should take to recover from an internal
inconsistency on a file system. Specify
action as panic, lock, or umount. These
values cause a forced system shutdown, a
file system lock to be applied to the file
system, or the file system to be forcibly
unmounted, respectively. The default is
quota Quotas are turned on for the file system.
Remounts a file system with a new set of
options. All options not explicitly set
with remount revert to their default
rq Read-write with quotas turned on.
Equivalent to rw, quota.
ro | rw
Read-only or read-write. Default is rw.
suid | nosuid
Allow or disallow setuid/setgid execution.
The default is suid. This option also
allows/disallows opening any device-special
entries that appear within the filesystem.
This option is highly recommended whenever
the file system is shared via NFS with the
root= option, because, without it, NFS
clients could add setuid programs to the
server, or create devices that could open
-O Overlay mount. Allow the file system to be
mounted over an existing mount point, making the
underlying file system inaccessible. If a mount
is attempted on a pre-existing mount point
without setting this flag, the mount will fail,
producing the error "device busy".
The mount_ufs command supports the xattr flag, to allow the
creation and manipulation of extended attributes. See
fsattr(5) for a description of extended attributes. The
xattr flag is always on.
When a UFS file system is mounted with logging enabled, file
system transactions that free blocks from files might not
actually add those freed blocks to the file system's free
list until some unspecified time in the future. This
behavior improves file system performance but does not con-
form to the POSIX, Single UNIX Specification, SPARC Confor-
mance Definition, System V Application Binary Interface,
System V Interface Definition, and X/Open Portability Guide
Standards, which require that freed space be available
immediately. To enable standards conformance regarding file
deletions or to address the problem of not being able to
grow files on a relatively full UFS file system even after
files have been deleted, disable UFS logging.
table of mounted file systems
list of default parameters for each file system
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Availability | SUNWcsu |
fsck(1M), fsck_ufs(1M), mount(1M), mountall(1M), fcntl(2),
mount(2), stat(2), mnttab(4), vfstab(4), attributes(5),
Since the root (/) file system is mounted read-only by the
kernel during the boot process, only the remount option (and
options that can be used in conjunction with remount) affect
the root (/) entry in the /etc/vfstab file.
File system transactions that free blocks from files might
not immediately add the freed blocks to the file system's
free list. This behavior occurs in a system that has a UFS
file system mounted with logging enabled.
This behavior improves file system performance, but does not
conform to the following standards:
o POSIX, Single UNIX Specification
o SPARC Conformance Definition
o System V Application Binary Interface
o System V Interface Definition
o X/Open Portability Guide
These standards require that freed space be available
Consider disabling UFS logging under the following condi-
o You want to enable standards conformance regarding
o You encounter problems creating or growing files
immediately after files have been deleted on a rela-
tively full file system.
Man(1) output converted with