Chapter 16. Mounting file systems
As a system administrator, you can mount file systems on your system to access data on them.
16.1. The Linux mount mechanism
These are the basic concepts of mounting file systems on Linux.
On Linux, UNIX, and similar operating systems, file systems on different partitions and removable devices (CDs, DVDs, or USB flash drives for example) can be attached to a certain point (the mount point) in the directory tree, and then detached again. While a file system is mounted on a directory, the original content of the directory is not accessible.
Note that Linux does not prevent you from mounting a file system to a directory with a file system already attached to it.
When mounting, you can identify the device by:
-
a universally unique identifier (UUID): for example,
UUID=34795a28-ca6d-4fd8-a347-73671d0c19cb -
a volume label: for example,
LABEL=home -
a full path to a non-persistent block device: for example,
/dev/sda3
When you mount a file system using the mount command without all required information, that is without the device name, the target directory, or the file system type, the mount utility reads the content of the /etc/fstab file to check if the given file system is listed there. The /etc/fstab file contains a list of device names and the directories in which the selected file systems are set to be mounted as well as the file system type and mount options. Therefore, when mounting a file system that is specified in /etc/fstab, the following command syntax is sufficient:
Mounting by the mount point:
# mount directoryMounting by the block device:
# mount device
Additional resources
-
mount(8)man page on your system - How to list persistent naming attributes such as the UUID.
16.2. Listing currently mounted file systems
List all currently mounted file systems on the command line by using the findmnt utility.
Procedure
To list all mounted file systems, use the
findmntutility:$ findmnt
To limit the listed file systems only to a certain file system type, add the
--typesoption:$ findmnt --types fs-typeFor example:
Example 16.1. Listing only XFS file systems
$ findmnt --types xfs TARGET SOURCE FSTYPE OPTIONS / /dev/mapper/luks-5564ed00-6aac-4406-bfb4-c59bf5de48b5 xfs rw,relatime ├─/boot /dev/sda1 xfs rw,relatime └─/home /dev/mapper/luks-9d185660-7537-414d-b727-d92ea036051e xfs rw,relatime
Additional resources
-
findmnt(8)man page on your system
16.3. Mounting a file system with mount
Mount a file system by using the mount utility.
Prerequisites
Verify that no file system is already mounted on your chosen mount point:
$ findmnt mount-point
Procedure
To attach a certain file system, use the
mountutility:# mount device mount-point
Example 16.2. Mounting an XFS file system
For example, to mount a local XFS file system identified by UUID:
# mount UUID=ea74bbec-536d-490c-b8d9-5b40bbd7545b /mnt/data
If
mountcannot recognize the file system type automatically, specify it using the--typesoption:# mount --types type device mount-point
Example 16.3. Mounting an NFS file system
For example, to mount a remote NFS file system:
# mount --types nfs4 host:/remote-export /mnt/nfs
Additional resources
-
mount(8)man page on your system
16.4. Moving a mount point
Change the mount point of a mounted file system to a different directory by using the mount utility.
Procedure
To change the directory in which a file system is mounted:
# mount --move old-directory new-directory
Example 16.4. Moving a home file system
For example, to move the file system mounted in the
/mnt/userdirs/directory to the/home/mount point:# mount --move /mnt/userdirs /home
Verify that the file system has been moved as expected:
$ findmnt $ ls old-directory $ ls new-directory
Additional resources
-
mount(8)man page on your system
16.5. Unmounting a file system with umount
Unmount a file system by using the umount utility.
Procedure
Try unmounting the file system using either of the following commands:
By mount point:
# umount mount-pointBy device:
# umount device
If the command fails with an error similar to the following, it means that the file system is in use because of a process is using resources on it:
umount: /run/media/user/FlashDrive: target is busy.If the file system is in use, use the
fuserutility to determine which processes are accessing it. For example:$ fuser --mount /run/media/user/FlashDrive /run/media/user/FlashDrive: 18351
Afterwards, stop the processes using the file system and try unmounting it again.
16.6. Mounting and unmounting file systems in the web console
To be able to use partitions on RHEL systems, you need to mount a file system on the partition as a device.
You also can unmount a file system and the RHEL system will stop using it. Unmounting the file system enables you to delete, remove, or re-format devices.
Prerequisites
-
The
cockpit-storagedpackage is installed on your system.
You have installed the RHEL 8 web console.
For instructions, see Installing and enabling the web console.
- If you want to unmount a file system, ensure that the system does not use any file, service, or application stored in the partition.
Procedure
Log in to the RHEL 8 web console.
For details, see Logging in to the web console.
- Click the Storage tab.
- In the Storage table, select a volume from which you want to delete the partition.
- In the GPT partitions section, click the menu button, next to the partition whose file system you want to mount or unmount.
- Click or .
16.7. Common mount options
The following table lists the most common options of the mount utility. You can apply these mount options using the following syntax:
# mount --options option1,option2,option3 device mount-point
| Option | Description |
|---|---|
|
| Enables asynchronous input and output operations on the file system. |
|
|
Enables the file system to be mounted automatically using the |
|
|
Provides an alias for the |
|
| Allows the execution of binary files on the particular file system. |
|
| Mounts an image as a loop device. |
|
|
Default behavior disables the automatic mount of the file system using the |
|
| Disallows the execution of binary files on the particular file system. |
|
| Disallows an ordinary user (that is, other than root) to mount and unmount the file system. |
|
| Remounts the file system in case it is already mounted. |
|
| Mounts the file system for reading only. |
|
| Mounts the file system for both reading and writing. |
|
| Allows an ordinary user (that is, other than root) to mount and unmount the file system. |
