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Terms and concepts

Access Control List

The Access Control List (ACL) mechanism can be used to control other Allas users' access to your buckets.

Billing unit

Billing units describe the consumption of computing and storage resources in the CSC systems. In Allas, the amount of data stored consumes billing units.

See Billing and Quotas


A bucket is a container for objects that may also include metadata describing the bucket.


A checksum is a hashed string computed of an object to observe whether the object has changed (data integrity). You can display the checksum using the command md5sum.


The client software is used to access an object storage service, such as Allas. There are three types of clients:

  • Web browser based access via the OpenStack Horizon web interface for basic graphical usage.
  • Command-line clients such as Swift and s3cmd for power users.
  • Programmable interface (API) for those who integrate software.


Metadata describes an object or bucket. It can be used to search for objects. It is used via key-value pairs (for example, name: John).

Object lifecycle

Object lifecycle Can be configured to automatically remove objects from Allas. Lifecycle is configured in the bucket level, where multiple expiration periods can be defined. Lifecycle is applied to the objects in the bucket based on their matching tags and/or prefixes. See an example in the s3 client tool documentation

Object storage

Object storage refers to a computer data storage that manages data as objects instead of files or blocks. Typically, an object consists of the data itself, metadata and a unique identifier. In general, the data can be anything, e.g. an image or audio.


The OpenStack cloud management middleware can be used to access Allas. The OpenStack Horizon web interface offers some basic functionalities for data management in Allas.

See OpenStack for more information.

Pseudo folder

Buckets cannot contain other buckets. You can, however, use so-called pseudo folders.

If an object's name contains a forward slash /, it is interpreted as a folder separator. These are shown as folder listings when accessing the data via the web interface. These pseudo folders are automatically added if you upload whole folders using a command line client.

For example, if you add two objects

in a bucket, listing the bucket will display a folder called fishes and the two files in it.


The Allas quota defines the maximum amount of data (capacity) the project is allowed to store in Allas.

See Billing and quotas

Last update: January 7, 2021