DataHub

Overview

The DataHub allows to:

• Bring data close to the computing to exploit it efficiently.
• Publish a dataset and make it available to a specific community or worldwide across federated sites.

The main features offered by the DataHub are:

• Discovery of data via a central portal.
• Access to data conforming to required policies which may be:
  1. unauthenticated open access;
  2. access after user registration or
  3. access restricted to members of a Virtual Organization (VO).
     This access may be via a GUI (e.g. a webpage) or an API (e.g. programmatic access to the data)
• Replication of data from data providers for resiliency and availability purposes. Replication may take place either on­demand or automatically. Replication will require the introduction of a file catalogue to enable tracking of logical and physical copies of data.
• Access to data from the AppDB to enable VOs to associate appropriate data with matching Virtual Appliances
• Authentication and Authorization Infrastructure (AAI) integration between the EGI DataHub and with other EGI components and with user communities existing infrastructure
• File catalog to track replication of data: logical and physical file

It is based on the OneData technology.

Motivations

• Putting up a (scalable) distributed data infrastructure needs specific expertise, resources and knowledge
• No easy way to discover and transfer data
• No easy way of making data (publicly) accessible without transferring it with a sharing service
• No easy way of combining multiple datasets from different data providers
• Users need to access data locally and from compute resources

Components and concepts

Space

a virtual volume where users will organize their data. A space is supported by one or multiple Oneproviders providing actual storage resources

Onezone

a central component federating providers. It takes care of Authentication and Authorization and other management tasks (like space creation). EGI DataHub is a Onezone instance.

EGI DataHub

the central Onedata Onezone instance of the EGI Federation. Single Sign On (SSO) with all the connected storage providers (Oneprovider) is guaranteed through EGI Check-in

Oneprovider

a data management component deployed in the data centres, provisioning data and managing transfers. A Oneprovider is typically deployed at a site near the local storage resources, and can access local storage resources over multiple connectors (CEPH, POSIX,...). A default one is operated for EGI by CYFRONET.

Oneclient

a client application providing access to the spaces through a FUSE mount point (local POSIX access). Spaces are accessible as if they were part of the local file system. Oneclient can be used from VM, containers, desktop,...

Web interfaces and APIs are also available

Highlighted features

Using the EGI DataHub web interface it's possible to manage the space.

Using Oneclient it's possible to mount a space locally, and access it over a POSIX interface, using files as they were stored locally. The file's blocks are downloaded on demand.

In Onedata the file distribution is done on a block basis, blocks will be replicated on the fly, and it's possible to instrument the replication.

Three different formats of metadata can be attached to files: basic (key/value), JSON and RDF. The metadata can be managed using the Web interface and the APIs. It's also possible to create indexes and query them.

It's possible to view the popularity of a file and manage smart caching.