Overview of Mounting File Systems
After you create a file system, you need to make it available
to the system so that you can use it. You make a file
system available by mounting it, which attaches the file system to the system
directory tree at the specified mount point. The root (/) file system is
always mounted.
The following table provides guidelines on mounting file systems based on how you
use them.
Mount Type Needed |
Suggested Mount Method |
|---|
Local or remote file systems that need
to be mounted infrequently |
The mount command that you type manually from the command
line. |
Local file systems that need to be mounted frequently |
The /etc/vfstab file, which
mounts the file system automatically when the system is booted in multi user
state. |
Remote file systems,, such as home directories, that need to be mounted frequently |
The /etc/vfstab file, which automatically mounts the file system when the system is booted in multiuser state. AutoFS, which automatically mounts the file system when you access it or unmounts the file system when you change to another directory.
To
enhance performance, you can also cache the remote file systems by using the
CacheFS file system. |
You can mount removable media that contains a file system by inserting the
media into the drive and running the volcheck command, if necessary. For more
information on mounting removable media, see Chapter 1, Managing Removable Media (Overview).
Commands for Mounting and Unmounting File Systems
The following table lists the commands in the /usr/sbin directory that you use
to mount and unmount file systems.
Table 19-1 Commands for Mounting and Unmounting File Systems
Command |
Description |
Man Page |
|---|
mount |
Mounts file systems and remote resources. |
mount(1M) |
mountall |
Mounts
all file systems that are specified in the /etc/vfstab file. The mountall command
runs automatically when the system enters multiuser mode. |
mountall(1M) |
umount |
Unmounts file systems and remote
resources. |
mount(1M) |
umountall |
Unmounts all file systems that are specified in the /etc/vfstab file. |
mountall(1M) |
Keep the following key points in mind when using the mount and
mountall commands:
The mount and mountall commands cannot mount a read/write file system that has known inconsistencies. If you receive an error message from the mount or mountall command, you might need to check the file system. See Chapter 22, Checking UFS File System Consistency (Tasks) for information on how to check the file system.
The umount and umountall commands do not unmount a file system that is busy. A file system is considered busy if one of the following is true:
A user is accessing a file or directory in the file system.
A program has a file open in that file system.
The file system is shared.
You can use the remount option when remounting from read-only access to read-write access only. You cannot remount from read-write access to read-only access.
Commonly Used Mount Options
The following table describes the commonly used options that you can specify with
the mount -o option. If you specify multiple options, separate them with
commas (no spaces). For example, -o ro,nosuid.
For a complete list of mount options for each file system type,
refer to the specific mount man page (for example, mount_ufs(1M)).
Table 19-2 Commonly Used -o Mount Options
mount Option |
File System |
Description |
|---|
bg | fg |
NFS |
If the
first mount attempt fails, retries another mount in the background (bg) or in
the foreground (fg). This option is safe for non critical vfstab entries. The
default is fg. |
hard | soft |
NFS |
Specifies the procedure if the server does not respond. The soft
option indicates that an error is returned. The hard option indicates that the retry
request is continued until the server responds. The default is hard. |
intr | nointr |
NFS |
Specifies whether keyboard
interrupts are delivered to a hung process while waiting for a response on
a hard-mounted file system. The default is intr (interrupts allowed). |
largefiles | nolargefiles |
UFS |
Enables you to
create files larger than 2 Gbytes. The largefiles option means that a file
system mounted with this option might contain files larger than 2 Gbytes. If
the nolargefiles option is specified, the file system cannot be mounted on a
system that is running Solaris 2.6 or compatible versions. The default is largefiles.
|
logging | nologging |
UFS |
Enables or disables logging for the file system. UFS logging is the process
of storing transactions (changes that comprise a complete UFS operation) into a log
before the transactions are applied to the UFS file system. Logging helps prevent
UFS file systems from becoming inconsistent, which means fsck can be bypassed.
Bypassing fsck reduces the time to reboot a system if it crashes, or
after a system is shut down uncleanly. The log is allocated from free
blocks on the file system, and is sized at about 1 Mbyte per
1 Gbyte of file system, up to a maximum of 64 Mbytes. The
default is logging. |
atime | noatime |
UFS |
Suppresses access time updates on files, except when they coincide
with updates to the time of the last file status change or the
time of the last file modification. For more information, see stat(2). This option
reduces disk activity on file systems where access times are unimportant (for example,
a Usenet news spool). The default is normal access time (atime) recording. |
remount |
All |
Changes the
mount options associated with an already-mounted file system. This option can generally be
used with any option except ro. However, what can be changed with this
option depends on the file system type. |
retry=n |
NFS |
Retries the mount operation when it
fails. n is the number of times to retry. |
ro | rw |
CacheFS, NFS, PCFS, UFS, HSFS |
Specifies
read/write (rw) or read-only (ro). If you do not specify this option, the
default is rw. The default option for HSFS is ro. |
suid | nosuid |
CacheFS, HSFS, NFS,
UFS |
Allows or disallows setuid execution. The default is to allow setuid execution. |
Field Descriptions for the /etc/vfstab File
An entry in the /etc/vfstab file has seven fields, which are described in
the following table.
Table 19-3 Field Descriptions for the /etc/vfstab File
Field Name |
Description |
|---|
device to mount |
This field identifies one of the following:
The block device name for a local UFS file system (for example, /dev/dsk/c0t0d0s0). The resource name for a remote file system (for example, myserver:/export/home). For more information about NFS, see System Administration Guide: IP Services. The block device name of the slice on which to swap (for example, /dev/dsk/c0t3d0s1). A directory for a virtual file system.
|
device to fsck |
The
raw (character) device name that corresponds to the UFS file system identified by
the device to mount field (for example, /dev/rdsk/c0t0d0s0). This field determines the raw interface
that is used by the fsck command. Use a dash (-) when there is
no applicable device, such as for a read-only file system or a remote
file system. |
mount point |
Identifies where to mount the file system (for example, /usr).
|
FS type |
Identifies the type of file system. |
fsck pass |
The pass number used by the
fsck command to decide whether to check a file system. When the field
contains a dash (-), the file system is not checked. Currently, the fsck pass
value in the /etc/vfstab file is ignored during the boot process. When the
field contains a zero, UFS file systems are not checked. However, non-UFS file
systems are checked. When the field contains a value greater than zero, the
file system is always checked. All file systems with a value of
1 in this field are checked one at a time in the order
they appear in the vfstab file. When the fsck command is run on
multiple UFS file systems that have fsck pass values greater than 1 and the
preen option (-o p) is used, the fsck command automatically checks the file systems on
different disks in parallel to maximize efficiency. Otherwise, the value of the pass
number does not have any effect. |
mount at boot |
Set to yes or no for
whether the file system should be automatically mounted by the mountall command when the
system is booted. Note that this field has nothing to do with
AutoFS. The root (/), /usr and /var file systems are not mounted from the
vfstab file initially. This field should always be set to no for these
file systems and for virtual file systems such as /proc and /dev/fd. |
mount options |
A list
of comma-separated options (with no spaces) that are used for mounting the file
system. Use a dash (-) to indicate no options. For a list of
commonly used mount options, see Table 19-2. |
Note - You must have an entry in each field in the /etc/vfstab file.
If there is no value for a field, be sure to specify
a dash (-). Otherwise, the system might not boot successfully. Similarly, white space should
not be used as a field value.
