Chapter 40Mounting and Unmounting File Systems (Tasks)
This chapter describes how to mount and unmount file systems.
This is a list of the step-by-step instructions in this chapter.
Overview of Mounting File Systems
After you create
a file system, you need to make it available to the system so 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 enter 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
that need to be mounted frequently, such as home directories | The /etc/vfstab file, which automatically
mounts the file system when the system is booted in multi-user state. AutoFS, which automatically mounts or unmounts the file system
when you access or change out of the directory.
To enhance performance, you can also cache the remote
file systems by using the CacheFS file system. |
You can mount 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 17, 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 40-1 Commands for Mounting and Unmounting File Systems
Command | Man Page | Description |
|---|
mount | mount(1M) | Mounts file systems and remote resources. |
mountall | mountall(1M) | Mounts all file systems that are specified in the /etc/vfstab
file. The mountall command runs automatically when the
system enters multiuser mode. |
umount | mount(1M) | Unmounts file systems and remote resources. |
umountall | mountall(1M) | Unmounts all file systems that are specified in the /etc/vfstab file. |
The mount and mountall commands
will not 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 43, Checking UFS File System Consistency (Tasks) for information on how to check the file system.
The umount and umountall commands
will 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.
If a program has a file open in that file system.
If the file system is shared.
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 pages (for example, mount_ufs(1M)).
Table 40-2 Commonly Used -o Mount Options
Option | File System | Description |
|---|
bg | fg | NFS | If the first mount attempt fails, retries 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 process that is hung 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, but it is not required. 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 make up 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 shutdown uncleanly. The log is allocated from free blocks on
the file system, and is sized at approximately 1 Mbyte per 1 Gbyte of file
system, up to a maximum of 64 Mbytes. The default is nologging. |
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, but what can be changed with this option is dependent 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 40-3 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 type.
|
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. When the field contains a zero, UFS file systems
are not checked but 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 one 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 40-2. |
Note - You must have an entry in each field in the /etc/vfstab file. If there is no value for the field, be sure to enter a
dash (-). Otherwise, the system might not boot successfully.
Similarly, white space should not be used in a field value.
|
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