Managing Directory Quota

Directory quotas in GlusterFS allows you to set limits on usage of the disk space by directories or volumes. The storage administrators can control the disk space utilization at the directory and/or volume levels in GlusterFS by setting limits to allocatable disk space at any level in the volume and directory hierarchy. This is particularly useful in cloud deployments to facilitate utility billing model.

Note For now, only Hard limits are supported. Here, the limit cannot be exceeded and attempts to use more disk space or inodes beyond the set limit is denied.

System administrators can also monitor the resource utilization to limit the storage for the users depending on their role in the organization.

You can set the quota at the following levels:

Directory level – limits the usage at the directory level
Volume level – limits the usage at the volume level

Note You can set the disk limit on the directory even if it is not created. The disk limit is enforced immediately after creating that directory.

Enabling Quota

You must enable Quota to set disk limits.

To enable quota:

Use the following command to enable quota:

# gluster volume quota VOLNAME enable

For example, to enable quota on the test-volume:

# gluster volume quota test-volume enable
Quota is enabled on /test-volume

Disabling Quota

You can disable Quota, if needed.

To disable quota:

Use the following command to disable quota:

# gluster volume quota VOLNAME disable

For example, to disable quota translator on the test-volume:

    # gluster volume quota test-volume disable
    Quota translator is disabled on /test-volume

Setting or Replacing Disk Limit

You can create new directories in your storage environment and set the disk limit or set disk limit for the existing directories. The directory name should be relative to the volume with the export directory/mount being treated as "/".

To set or replace disk limit:

Set the disk limit using the following command:
```
# gluster volume quota VOLNAME limit-usage DIR HARD_LIMIT
```
For example, to set limit on data directory on the test-volume where data is a directory under the export directory:
```
# gluster volume quota test-volume limit-usage /data 10GB
Usage limit has been set on /data
```
Note In a multi-level directory hierarchy, the strictest disk limit will be considered for enforcement. Also, whenever quota limit is set for the first time, an auxiliary mount point will be created under /var/run/gluster/. This is just like any other mount point with some special permissions and remains until quota is disabled. This mount point is being used by quota to set and display limits and lists respectively.

Displaying Disk Limit Information

You can display disk limit information on all the directories on which the limit is set.

To display disk limit information:

Display disk limit information of all the directories on which limit is set, using the following command:
```
# gluster volume quota VOLNAME list
```
For example, to see the set disks limit on the test-volume:
```
# gluster volume quota test-volume list
/Test/data    10 GB       6 GB
/Test/data1   10 GB       4 GB
```
Display disk limit information on a particular directory on which limit is set, using the following command:
```
# gluster volume quota VOLNAME list DIR
```
For example, to view the set limit on /data directory of test-volume:
```
# gluster volume quota test-volume list /data
/Test/data    10 GB       6 GB
```

Displaying Quota Limit Information Using the df Utility

You can create a report of the disk usage using the df utility by taking quota limits into consideration. To generate a report, run the following command:

    # gluster volume set VOLNAME quota-deem-statfs on

In this case, the total disk space of the directory is taken as the quota hard limit set on the directory of the volume.

Note The default value for quota-deem-statfs is on when quota is enabled and it is recommended to keep quota-deem-statfs on.

The following example displays the disk usage when quota-deem-statfs is off:

    # gluster volume set test-volume features.quota-deem-statfs off
    volume set: success
    # gluster volume quota test-volume list
    Path        Hard-limit    Soft-limit     Used     Available
    -----------------------------------------------------------
    /              300.0GB        90%        11.5GB     288.5GB
    /John/Downloads 77.0GB        75%        11.5GB     65.5GB

Disk usage for volume test-volume as seen on client1:

    # df -hT /home
    Filesystem           Type            Size  Used Avail Use% Mounted on
    server1:/test-volume fuse.glusterfs  400G   12G  389G   3% /home

The following example displays the disk usage when quota-deem-statfs is on:

    # gluster volume set test-volume features.quota-deem-statfs on
    volume set: success
    # gluster vol quota test-volume list
    Path        Hard-limit    Soft-limit     Used     Available
    -----------------------------------------------------------
    /              300.0GB        90%        11.5GB     288.5GB
    /John/Downloads 77.0GB        75%        11.5GB     65.5GB

Disk usage for volume test-volume as seen on client1:

    # df -hT /home
    Filesystem            Type            Size  Used Avail Use% Mounted on
    server1:/test-volume  fuse.glusterfs  300G   12G  289G   4% /home

The quota-deem-statfs option when set to on, allows the administrator to make the user view the total disk space available on the directory as the hard limit set on it.

Updating Memory Cache Size

Setting Timeout

For performance reasons, quota caches the directory sizes on client. You can set timeout indicating the maximum valid duration of directory sizes in cache, from the time they are populated.

For example: If there are multiple clients writing to a single directory, there are chances that some other client might write till the quota limit is exceeded. However, this new file-size may not get reflected in the client till size entry in cache has become stale because of timeout. If writes happen on this client during this duration, they are allowed even though they would lead to exceeding of quota-limits, since size in cache is not in sync with the actual size. When timeout happens, the size in cache is updated from servers and will be in sync and no further writes will be allowed. A timeout of zero will force fetching of directory sizes from server for every operation that modifies file data and will effectively disables directory size caching on client side.

To update the memory cache size:

Use the following command to update the memory cache size:

# gluster volume set VOLNAME features.quota-timeout time

For example, to update the memory cache size for every 5 seconds on test-volume:

# gluster volume set test-volume features.quota-timeout 5
Set volume successful

Setting Alert Time

Alert time is the frequency at which you want your usage information to be logged after you reach the soft limit.

To set the alert time:

Use the following command to set the alert time:
```
# gluster volume quota VOLNAME alert-time time
```
Note

The default alert-time is one week.

For example, to set the alert time to one day:
```
# gluster volume quota test-volume alert-time 1d
volume quota : success
```

Removing Disk Limit

You can remove set disk limit, if you do not want quota anymore.

To remove disk limit:

Use the following command to remove the disk limit set on a particular directory:
```
# gluster volume quota VOLNAME remove DIR
```
For example, to remove the disk limit on /data directory of test-volume:
```
# gluster volume quota test-volume remove /data
Usage limit set on /data is removed
```