diff --git a/doc/ADDITIONAL_STORAGE.md b/doc/ADDITIONAL_STORAGE.md
new file mode 100644
index 0000000..26126eb
--- /dev/null
+++ b/doc/ADDITIONAL_STORAGE.md
@@ -0,0 +1,118 @@
+### Adding storage space
+
+Solution I. allows you to add a link to a local or remote folder.  
+Solution II. allows to move the main storage space of Nextcloud.
+
+#### I. Add an external storage space
+
+Parameter =>[Administration] External storage.
+
+At the bottom of the list you can add a folder (It is possible to define a subfolder using the `folder/subfolder` convention.)  
+Select a storage type and specify the requested connection information.  
+You can restrict this folder to one or more nextcloud users with the column `Available for`.  
+With the gear you can allow or prohibit previewing and file sharing.  
+Finally click on the check mark to validate the folder.
+
+#### II. Migrate Nextcloud data to a larger partition
+
+**Note**: The following assumes that you have a hard disk mounted on `/media/storage`. Refer to[this article](/external_storage) to prepare your system.
+
+**Note**: Replace `nextcloud` with the name of its instance, if you have several Nextcloud apps installed.
+
+First turn off the web server with the command:
+```bash
+systemctl stop nginx  
+```
+
+##### Choice of location
+
+**Case A: Blank storage, exclusive to Nextcloud**
+
+For the moment only root can write to it in `/media/storage`, which means that NGINX and Nextcloud will not be able to use it.
+
+```bash
+chown -R nextcloud:nextcloud /media/storage
+chmod 775 -R /media/storage
+```
+
+**Case B: Shared storage, data already present, Nextcloud data in a subfolder**
+
+If you want to use this disk for other applications, you can create a subfolder belonging to Nextcloud.
+
+```bash
+mkdir -p /media/storage/nextcloud_data
+chown -R nextcloud /media/storage/nextcloud_data
+chmod 775 -R /media/storage/nextcloud_data
+```
+
+##### Migrate data
+
+Migrate your data to the new disk. To do this *(be patient, it can take a long time)*:
+
+```bash
+Case A: cp -ia /home/yunohost.app/nextcloud /media/storage
+Case B: cp -ia /home/yunohost.app/nextcloud /media/storage/nextcloud_data
+```
+
+The `i` option allows you to ask yourself what to do if there is a file conflict, especially if you overwrite an old Owncloud or Nextcloud data folder.  
+To check that everything went well, compare what these two commands display (the content must be identical):
+
+```bash
+ls -la /home/yunohost.app/nextcloud
+
+Case A: ls -al /media/storage
+Case B: ls -al /media/storage/nextcloud_data/nextcloud
+```
+
+##### Configure Nextcloud
+
+To inform Nextcloud of its new directory, modify the `/var/www/nextcloud/config/config.php` file with the command:
+
+```bash
+nano /var/www/nextcloud/config/config.php
+```
+
+Look for the line:
+
+```bash
+'datadirectory' => '/home/yunohost.app/nextcloud/data',
+```
+
+That you modify:
+
+```bash
+CASE A:'datadirectory' =>'/media/storage',
+CASE B:'datadirectory' =>'/media/storage/nextcloud_data/nextcloud/data',
+```
+
+Save it with `ctrl+x` then `y` or `o` (depending on your server locale).
+
+Restart the web server:
+
+```bash
+systemctl start nginx
+```
+
+Add the.ocdata file
+```bash
+CASE A: nano /media/storage/.ocdata
+CASE B: nano /media/storage/nextcloud_data/nextcloud/data/.ocdata
+```
+Add a space to the file to be able to save it
+
+Back up with `ctrl+x` then `y` or `o` (depending on your server locale).
+
+Run a scan of the new directory by Nextcloud:
+
+```bash
+cd /var/www/nextcloud
+sudo -u nextcloud php8.1 --define apc.enable_cli=1 files:scan --all
+```
+
+Update the YunoHost setting, so automatic upgrades and backups know where the datadir is located:
+```bash
+Case A: yunohost app setting nextcloud datadir -v /media/storage
+Case B: yunohost app setting nextcloud datadir -v /media/storage/nextcloud_data/nextcloud/data/
+```
+
+It's over now. Now test if everything is fine, try connecting to your Nextcloud instance, upload a file, check its proper synchronization.