User quota in Linux step by step

 

Linux Admin – Quota Management

As a Linux administrator, quota management is an important aspect of managing file systems and controlling disk usage by users. Quotas allow you to set limits on the amount of disk space a user or a group can consume. Here's a general guide on how to manage quotas in Linux:

         

    Enabling Quota Management in C Linux is basically a 4 step process –

• Step 1 − Enable quota management for groups and users in /etc/fstab.

• Step 2 − Remount the filesystem.

• Step 3 − Create Quota database and generate disk usage table.

• Step 4 − Assign quota policies.

• Enable Quota Management in /etc/fstab

• First, we want to backup our /etc/fstab filen −

[root@localhost ~]#  cp -r /etc/fstab ./

We now have a copy of our known working /etc/fstab in the current working directory.

We made the following changes in the options section of /etc/fstab for the volume or Label to where quotas are to be applied for users and groups.

• usrquota

• grpquota

 As you can see, we are using the xfs filesystem. When using xfs there are extra manual steps   involved. /home is on the same disk as /. Further investigation shows / is set for noquota, which is  a kernel level mounting option. We must re-configure our kernel boot options.

[root@localhost ~]# mount | grep ' / '
/dev/mapper/cl-root on / type xfs (rw,relatime,seclabel,attr2,inode64,noquota)
[root@localhost rdc]#

Reconfiguring Kernel Boot Options for XFS File Systems

To reconfigure kernel boot options for XFS file system in Linux, you can follow these steps:

1. Edit the bootloader configuration file: The specific file you need to edit depends on your Linux distribution. For example, if you are using GRUB as the bootloader, you can edit the /etc/default/grub file. Use a text editor with root privileges to open the file.

2. Locate the GRUB_CMDLINE_LINUX line: Within the bootloader configuration file, you should find a line starting with GRUB_CMDLINE_LINUX. This line contains the kernel command-line options.
   Add or modify the options: Add or modify the options related to the XFS file system. Some common options for XFS include xfs, rootflags, and xfs_options. Here are a few examples

3. • To enable XFS support: Add xfs to the GRUB_CMDLINE_LINUX line.
   • To specify XFS file system options: Use the rootflags parameter. For example, rootflags=defaults,noatime.
   • To pass specific XFS options: Use the xfs_options parameter. For example, xfs_options=allocsize=64m,inode64.

4. Note: Make sure to separate multiple options with spaces.

5. Save the changes: After making the necessary modifications, save the file and exit the text editor.
6. Update the bootloader: Run the appropriate command to update the bootloader configuration based on your distribution. For example, with GRUB, you can use the grub-mkconfig command or update-grub command. This step ensures that the changes take effect during the next boot.
7. Reboot your system: Once the bootloader is updated, reboot your system to apply the new kernel boot options.

After the reboot, the kernel will use the updated boot options for the XFS file system.

Remount the file system linux

To remount a file system in Linux, you can use the mount command with the appropriate options. Here's how you can remount a file system:

1. Identify the current mount point: Determine the mount point of the file system you want to remount. You can use the df command to list all mounted file systems along with their mount points. For example, if you want to remount the /dev/sda1 partition, you might see something like this:

In this example, the mount point is /mnt/myfilesystem.

2. Unmount the file system: Before remounting, you need to unmount the file system. Use the umount command followed by the mount point. For instance:

Make sure you have the necessary permissions or use sudo to execute the command with root privileges.

3. Remount the file system: Once the file system is unmounted, you can remount it with the desired options. Use the mount command along with the appropriate options. For example, to remount the file system with read-write permissions, you can use:

Here, -o remount,rw specifies the options to remount the file system as read-write. Adjust the command based on your requirements and the specific file system you want to remount.

Note: If you want to specify additional mount options (e.g., changing file system type or modifying options), you can include them in the mount command as well.

4. Verify the remount: You can use the mount or df command again to verify that the file system has been successfully remounted. Check the mount options and ensure that the changes you intended are reflected.

Create Quota Database Files

Linux is now capable of working with disk quotas on /home. To enable full quota supprt, we must run the quotacheck command.

quotacheck will create two files −

• aquota.user

• aquota.group

These are used to store quota information for the quota enabled disks/partitions.
Following are the common quotacheck switches.

SWITCH	ACTION
-u	Checks for user quotas
-g	Checks for group quotas
-c	Quotas should be enabled for each file system with enables quotas
-v	Displays verbose output

Add Quota Limits Per User linux

To add quota limits per user in Linux, you can use the edquota command. This command allows you to set disk quota limits for individual users on a file system. Here's how you can do it:

1 Identify the file system: Determine the file system on which you want to set the quota limits. Make sure quotas are enabled on that file system. You can check the /etc/fstab file or use the mount command to find the mount point of the file system

2 Set quota limits: Use the edquota command to set the quota limits for a specific user. Here's the basic syntax:

Replace username with the username of the user for whom you want to set the quota limits. Replace /mnt/myfilesystem with the mount point of the file system on which you want to set the quotas.

Define the quota limits: After executing the command, the edquota command will open an editor (usually Vi or Vim) with the current quota settings for the specified user. You can modify these values to set the desired quota limits.
The file typically contains columns for Block soft limit, Block hard limit, Inode soft limit, and Inode hard limit. The soft limits define the threshold where users will start receiving warnings, while the hard limits are the actual quota limits. You can set these values based on your requirements.

For example:
Filesystem                   blocks       soft       hard     inodes     soft     hard
/dev/sda1                        100        10         20          5        0        0

In this example, the soft block limit is set to 10 and the hard block limit is set to 20.

Save and exit the editor: After setting the desired quota limits, save the changes and exit the editor. In Vi or Vim, you can typically do this by pressing Esc, followed by :wq and then pressing Enter.

Apply the changes: The quota limits will take effect immediately. The user will be subject to the defined quota limits on the specified file system.

You can repeat these steps for each user you want to set quota limits for. Remember to adjust the mount point and user name accordingly.

Note: Make sure you have the necessary permissions or use sudo to execute the edquota command with root privileges since modifying quotas typically requires administrative access.