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EXT4 and XFS

This page covers disk quota management for EXT4/XFS.

Both EXT4 and XFS use the built-in quota management services in linux.

warning

Please read About Quotas before continuing

Configure Filesystem​

How to format and mount a device for use with quotas

I understand the risks and Pelican is not Liable for anything that breaks
warning

Enabling quotas for / is difficult, as it requires booting a live disk to change.

We do not recommended this!

These examples use the following:
/dev/sdb as the device formatted as EXT4 enabling only project quotas.
/var/lib/pelican/volumes/ as the mount point and data directory

Format Device​

mkfs.ext4 will format the disk with the ext4 filesystem

  • The O flag is the enable Feature Options
    • enable quotas while formatting
  • The E flag is for Extended Options
    • set the quota type as project
mkfs.ext4 -O quota -E quotatype=prjquota /dev/sdb
warning

You need to update fstab so the disk mounts automatically on boot with quotas enabled.

Add to fstab​

get device UUID​

The disk UUID is the best option for mounting the correct device via fstab.

lsblk /dev/sdb -no UUID
# example output
6c3b1734-3db4-4368-9bee-58651731b206

add new mount to fstab​

/etc/fstab
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
# / was on /dev/sda1 during installation
UUID=8529a07b-28bc-4296-848a-a185aaf11e94 /               ext4    errors=remount-ro 0       1
UUID=6c3b1734-3db4-4368-9bee-58651731b206 /var/lib/pelican/volumes/ ext4 defaults,prjquota 0 1

For more information on fstab check the Arch Linux fstab docs

warning

Depending on the OS you may need to refresh services to be able to mount the partition after updating fstab.

It is often easier to reboot and have the disk mount on boot.

Advanced EXT4 Quota Management​

danger

The following section is for manual management of quotas.

I understand
danger

You should never need to go here, this is your last warning.

I agree and Pelican is not Liable for anything that breaks

Manually Manage Quotas​

Limits for the servers are managed on a "project" level so they can be assigned per-directory.

Add A New Project​

To add a new project 2 files must be edited.

First is the projid file which is formatted where each line is in the project_name:project_id format as seen below

  • Pelican will use the server UUID as the project name
  • Make sure the ID is not already being used.
/etc/projid
235844d3-9258-4846-bb04-bcff209ccf9a:1
b91d5528-d53f-4586-8d5c-682027f74a36:2

Second is the projects file which is formatted where each line is in the project_id:path_to_directory format as seen below

/etc/projects
1:/var/lib/pelican/volumes/235844d3-9258-4846-bb04-bcff209ccf9a
2:/var/lib/pelican/volumes/b91d5528-d53f-4586-8d5c-682027f74a36

Set directory attributes​

The project attribute must be set on the directory to track quota usage.

The chattr command changes attribute for files and directories.

  • The + and - operators add or remove attributes
    • The P makes it so files and directories created in the directory will inherit the project id of the directory.
      • The project id and directory must match
  • The p flag is for the project id
chattr +P -p ${project_id} ${path_to_directory}

Example:

chattr +P -p 1 /var/lib/pelican/volumes/235844d3-9258-4846-bb04-bcff209ccf9a

set quota limits​

The built in quota management uses blocks by default.

  • You can specify limits in bytes as well.

The setquota command sets the quota for any object that supports quotas.

  • The P flag sets the quota for a project
    • This can use the project id or name
    • The should be the server UUID as shown in the examples below
  • The soft limit would send a warning to a user
    • This is not used by Pelican and will be set to 0
  • The hard limit is set to the disk resource limit set in Pelican
  • Neither the block or inode/file grace sections will be used by Pelican.
  • The path for either the device or the mount point
    • /dev/sdb/ or /var/lib/pelican/volumes/
setquota -P ${server_uuid} ${soft_limit} ${hard_limit} ${block_grace} ${inode_grace} ${path}

Example:
setting a hard limit, in Gigabytes

setquota -P 235844d3-9258-4846-bb04-bcff209ccf9a 0 10G 0 0 /var/lib/pelican/volumes/

get quota stats​

The repquota command will generate a report on the quotas for the specified device or mount path

  • The P flag will break down the report by project.
    • In this case it should be the server UUID that is the project name
  • The --human-readable flag sets the limits to be displayed in a human readable format. By default that is Megabytes
    • =g,g changes the output to be in Gigabytes (can be k, g, m, or t)

Example:

repquota -P --human-readable=g,g /var/lib/pelican/volumes/ # could also be /dev/sdb

Example Output

                        Block limits                File limits
Project         used    soft    hard  grace    used  soft  hard  grace
----------------------------------------------------------------------
235844d3-9258-4846-bb04-bcff209ccf9 --      3G      0G      5G             1g    0g    0g
cdb26bbb-963d-44b1-8353-360243032b1 --      2G      0G      2G             1g    0g    0g
note

TODO: Add documentation specifically for XFS