Handling Data & Storage Folders

Backend.AI supports dedicated storage to preserve user’s files. Since the files and directories of a compute session are deleted upon session termination, it is recommended to save them in a storage folder. List of storage folders can be found by selecting the Data & Storage page on the sidebar. You can see the information such as the folder name and ID, the NFS host name where the folder is located (Location), and folder access rights (Permission).

Folder list in Storage page

There are two types of storage folders. User folders can be created by normal users, and you can see that there is one user icon in the Type panel. On the other hand, Project folders can be recognized by an icon with multiple users in the panel. Project folders are created by domain admins, and normal users can only see project folders created for the project in which the users belong.

Storage Status on top of the folder list shows the following information:

  • Created: The number of folders that the user created.
  • Invited: The number of folers that the user was invited to share.
  • Capacity: The maximum number of folders that the user can create afterwards. This value depends on the resource policy applied to the user and cannot be changed without changing the resource policy. Folders that were not created by the user (eg. folders invited to share, or project folders) are not counted.

Check marks on the Owner panel in the folder list indicate the user created folders.

Storage status in Storage page


If there are lots of folders in the list, you can filter the list by using the search boxes on top of the list.

Create storage folder

You can create a storage folder with the desired name by clicking the NEW FOLDER button. Enter the name of the folder to be created in Folder name, and select one of User / Project for Type. (Depending on the server settings, only one of User or Project may be selectable.) When creating a project folder, the Project field must be set. The project folder will be bound to the project specified in the Project field, and only users belonging to the project can mount and use the project folder. After setting the values as desired, you can create a folder by clicking the CREATE button.

Folder creation dialog

The meaning of each fields that can be selected in the creation dialog is as follows.

  • Folder name: The name of the folder. You can enter up to 64 characters.
  • Host: NFS host to create folder. You can choose one if you have multiple NFS hosts.
  • Type: Determines the type of folder to be created. It can be set as User or Project. The User folder is a folder that users can create and use alone and the Project folder is a folder created by admin and shared by users in the project.
  • Usage Mode: You can set the purpose of the folder. There are three types of mode: General, Data, and Model. It is classified for the development of exclusive functions for Data & Model Stores in the future and currently there is no difference in UI depending on the purpose.
  • Project: Designates the project to which the folder belongs when creating a new project folder. Project folders must belong to a project. However, it does not play any role when creating a user folder.
  • Permission: Set permission of a project folder for project members. If this is set to “Read-Only”, project members cannot write to this folder inside their compute session.

Explore folder

You can click the folder icon in the Control panel to bring up a file explorer where you can view the contents of that folder.

Controls in folder item

You can see that directories and files inside the folder will be listed, if exists. Click a directory name in the Name panel to move to the directory. You can click the download button or delete button in the Actions panel to download it or delete it entirely from the directory. You can rename a file/directory as well. For more detailed file operations, you can mount this folder when creating a compute session, and then use a service like Terminal or Jupyter Notebook to do it.

File explorer of a storage folder

You can create a new directory on the current path with the NEW FOLDER button (in the file explorer), or upload a local file with the UPLOAD FILES button. All of these file operations can also be performed using the above-described method of mounting folders into a compute session.

The maximum length of file or directory inside a folder may depends on the host file system. But, it usually cannot exceed 255 characters.

To close file explorer, click the X button in the upper right.

Rename folder

If you have permission to rename the storage folder, you can rename it by clicking the edit icon in the Control panel. When you click the icon button, a rename dialog will appear. Write new folder name and then click UPDATE button.

Folder rename dialog

Delete folder

If you have permission to delete the storage folder, you can delete it by clicking the trash can icon in the Control panel. When you click the Delete button, a confirm dialog appears. To prevent accidental deletion, you have to enter the name of the folder to be deleted, explicitly.

Folder deletion dialog

The folders created here can be mounted when creating a compute session. Folders are mounted under the user’s default working directory, /home/work/, and the files stored in the mounted directory will not be deleted when the compute session is terminated. (However, if you delete the folder itself, it will be gone).

Automount folder

Data & Storage page has an Automount Folders tab. Click this tab to see a list of folders whose names prefixed with a dot (.). When you create a folder, if you specify a name that starts with a dot (.), it is added to the Automount Folders tab, not the Folders tab. Automount Folders are special folders that are automatically mounted in your home directory even if you do not mount them manually when creating a compute session. By using this feature, creating and using Storage folders such as .local, .linuxbrew, .pyenv, etc., you can configure a certain user packages or environments that do not change with different kinds of compute session.

For more detailed information on the usage of Automount folders, refer to examples of using automount folders.

Automount folders

Using FileBrowser

Backend.AI supports FileBrowser from version 20.09. FileBrowser is a program that helps you manage files on a remote server through a web browser. This is especially useful when uploading a directory from the user’s local machine.

Currently, Backend.AI provides a FileBrowser as an application of a compute session. Therefore, the following conditions are required to launch it.

  • User can create at least one compute session
  • User can allocated at least 1 core of CPU and 512 MB of memory
  • Image that supports FileBrowser has been installed

You can access FileBrowser in two ways.

  • Execute FileBrowser from file explorere dialog of a data folder in Data & Stroage page
  • Launch a compute session directly from a FileBrowser image on Sessions page

Execute FileBrowser from folder explorer dialog in Data & Storage page

Go to the Data & Storage page and open the file explorer dialog of target data folder. Click the folder icon in the Control column to the right of the data folder to open the file explorer.

first step to access FileBrowser

Click EXECUTE FILEBROWSER button in the upper-right corner of the explorer.

Folder explorer with FileBrowser

You can see the FileBrowser is opened in a new window. You can also see that the data folder you opened the explorer dialog becomes the root directory. From the FileBrowser window, you can freely upload, modify, and delete any directories and files.

FileBrowser with new window

When user clicks EXECUTE FILEBROWSER, Backend.AI automatically creates a dedicated compute session for the app. So, in the Sessions page, you should see FileBrowser compute session. It is user’s reponsibility to delete this compute session.

FileBrowser in session page


If you accidentally close the FileBrowser window and want to reopen it, just go to Sessions page and click the FileBrowser application icon of the FileBrowser compute session.


When you click EXECUTE FILEBROWSER button again in the data folder explorer, a new compute session will be created and a total of two FileBrowser sessions will appear.

Create a compute session with FileBrowser image

You can directly create a compute session with FileBrowser supported images. You need to mount at least one or more data folders to access them. You can use FileBrowser without a problem even if you do not mount any data folder, but every uploaded/updated files will be lost after the session is terminated.


The root directory of FileBrowser will be /home/work. Therefore, you can access any mounted data folders for the compute session.

Basic usage examples of FileBrowser

Here, we present some basic usage examples of FileBrowser in Backend.AI. Most of the FileBrowser operations are intuitive, but if you need more detailed guide, please refer to the FileBrowser documentation.

Upload local directory using FileBrowser

FileBrowser supports uploading one or more local directories while maintaining the tree structure. Click the upload button in the upper right corner of the window, and click Folder button. Then, local file explorer dialog will appear and you can select any directory you want to upload.


If you try to upload a file to a read-only folder, FileBrowser will raise a server error.


Let’s upload a directory with the following structure.

+-- test
|    +-- test2.txt
+-- test.txt

After selecting foo directory, you can see the directory just uploaded successfully.


You can also upload local files and directories by drag and drop.

Move files or directories to another directory

Moving files or directories in data folder is also possible from FileBrowser. You can move files or directories by following steps below.

  1. Select directories or files from FileBrowser.
  1. Click the arrow icon in the upper right corner of FileBrowser
  1. Select the destination
  1. Click MOVE button

You will see that moving operation is successfully finished.



FileBrowser is provided via application inside a compute session currently. We are planning to update FileBrowser so that it can run independently without creating a session.

Setting quota on XFS

If the underlying file system supports a per-directory or a per-project quota, such as XFS, Backend.AI can provide a per-folder quota. Administrators can set the quota limit through a resource policy, so if you want to increase the quota, contact the administrator. Within the policy limit, users can adjust the quota of their folders by clicking the setting icon for each data folder.

XFS quota setting

For more information on the per-folder quota on XFS, please refer to the following docs:

You can also see the current usage and capacity of a data folder in information dialog.

Vfolder information storage host xfs