> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Configure Systems to Mount Filesystems at or During Boot
> This guide explains how to mount filesystems manually and automatically during boot using fstab.
This guide explains how to mount filesystems both manually and automatically during boot. Previously, you learned how to create filesystems, but even after creation, a filesystem remains inaccessible until it is mounted. Mounting attaches a filesystem to a directory, allowing you to create and manage files on it. The sections below detail the step-by-step process of mounting filesystems and automating these operations using fstab.
## Mounting a Filesystem Manually
First, consider a temporary mount directory. In this example, we will mount an XFS filesystem (created in a previous lesson) located on `/dev/vdb1` at the directory `/mnt`.
Ensure that the directory exists and is empty before mounting the filesystem.
Run the following commands to mount the device, create a test file, and verify the mount:
```bash theme={null}
$ ls /mnt/
$ sudo mount /dev/vdb1 /mnt/
$ sudo touch /mnt/testfile
$ ls -l /mnt/
-rw-r--r--. 1 root root 0 Apr 8 09:03 testfile
```
You can confirm that the new file resides on the mounted filesystem using the `lsblk` command:
```bash theme={null}
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
vda 252:0 0 20G 0 disk
├─vda1 252:1 0 1M 0 part
├─vda2 252:2 0 1.8G 0 part /boot
├─vda3 252:3 0 18.2G 0 part
│ └─ubuntu--vg-ubuntu--lv 253:0 0 10G 0 lvm /
vdb 252:16 0 10G 0 disk
├─vdb1 252:17 0 4G 0 part
├─vdb2 252:18 0 4G 0 part
└─vdb3 252:19 0 2G 0 part
```
When finished, unmount the filesystem using the `umount` command (note the spelling without the “n”):
```bash theme={null}
$ sudo umount /mnt/
```
After unmounting, running `lsblk` will show that `/mnt` is empty.
## Automatic Mounting with fstab
Some filesystems mount automatically at boot time. For instance, `/dev/vda2` is typically mounted to `/boot` based on system configuration. To automate the mounting of additional filesystems such as the XFS filesystem on `/dev/vdb1`, you need to add an entry to the `/etc/fstab` file.
### Understanding the fstab File Format
The `/etc/fstab` file uses six fields for each filesystem entry:
1. **Block Device**: The partition (e.g., `/dev/vdb1`).
2. **Mount Point**: The directory to attach the filesystem (e.g., `/mybackups`).
3. **Filesystem Type**: The type of filesystem (e.g., `xfs` or `ext4`).
4. **Mount Options**: Commonly set to `defaults` but can be customized.
5. **Dump**: Typically set to `0` to disable dump backups.
6. **Pass**: Determines the order for filesystem checks at boot (usually `1` for the root and `2` for others; `0` disables checks).
Use a text editor like Vim to modify the `/etc/fstab` file. Always back up this file before making changes.
For example, to set up your XFS filesystem to mount at `/mybackups`, follow these steps:
1. Create the mount point directory:
```bash theme={null}
$ sudo mkdir -p /mybackups
```
2. Edit the `/etc/fstab` file:
```bash theme={null}
$ sudo vim /etc/fstab
```
3. Add the following lines to the file:
```fstab theme={null}
/dev/vda2 /boot ext4 defaults 0 1
/dev/vdb1 /mybackups xfs defaults 0 2
/dev/vdb2 /mybackups ext4 defaults 0 2
```
After saving the file, if a reboot is not performed immediately, notify Systemd of your changes so that they are applied at the next boot. On reboot, the filesystem on `/dev/vdb1` will be mounted automatically, and previously created files (for example, `testfile`) will become visible:
```bash theme={null}
$ sudo systemctl reboot
$ ls -l /mybackups/
-rw-r--r-- 1 root root 0 Apr 8 09:03 testfile
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
vda 252:0 0 20G 0 disk
├─vda1 252:1 0 1M 0 part
├─vda2 252:2 0 1.8G 0 part /boot
├─vda3 252:3 0 18.2G 0 part
└─ubuntu--vg-ubuntu--lv
253:0 0 10G 0 lvm /
vdb 252:16 0 10G 0 disk
└─vdb1 252:17 0 4G 0 part /mybackups
├─vdb2 252:18 0 4G 0 part
└─vdb3 252:19 0 2G 0 part
```
The above output confirms that the filesystem is mounted as expected.
## Configuring a Swap Partition
In a previous lesson, you created a swap partition at `/dev/vdb3`. To enable the swap partition automatically at boot, add the following line to the `/etc/fstab` file:
```bash theme={null}
$ sudo vim /etc/fstab
/dev/vdb3 none swap defaults 0 0
```
Key differences in the fstab fields for swap space include:
* The second field is set to `none` since swap space does not require a mount point.
* The third field specifies the type as `swap`.
* Both the dump and pass fields are set to `0` because swap space is not backed up or checked during boot.
A system reboot will ensure the swap partition is enabled automatically.
## Using UUIDs for Reliable Mounting
Sometimes, `/etc/fstab` entries reference devices by their UUID (Universally Unique Identifier) rather than device names. For example, instead of using `/dev/vda2`, an entry might use a UUID from `/dev/disk/by-uuid/`. The major advantage of using UUIDs is that they remain constant even if the device names change (for instance, due to varying connection orders).
To check the UUID of a block device, execute:
```bash theme={null}
$ sudo blkid /dev/vdb1
/dev/vdb1: LABEL="FirstFS" UUID="a51d7731-b033-4c07-b171-628ae951ea01" BLOCK_SIZE="512" TYPE="xfs" PARTUUID="21b2fb38-0cb9-104b-bd17-a60362e5aacd"
```
You can then update your fstab entry to use the UUID format, ensuring consistent device identification. To view all UUID assignments, run:
```bash theme={null}
$ ls -l /dev/disk/by-uuid/
```
Using UUIDs in your fstab file improves reliability, especially in complex storage environments.
## Final Thoughts
By following these guidelines, you can ensure that your filesystems and swap space are automatically mounted and enabled at boot, even when underlying device names change. For more detailed information on fstab and mounting options, refer to the manual page:
```bash theme={null}
man fstab
```
This concludes our guide on configuring systems to mount filesystems at boot. Happy computing!