Metadata is data about data. You can add metadata in a terminal window using the imeta commands after giving QuickShare read/write permissions. iRODS metadata (imeta) includes user-defined and iRODS system attributes stored in the iCAT database related to a data object, collection, resource, or user, etc. For information on using iCommands, see Sharing Data from the Command Line (iCommands).
About the metadata databases
Prior to the 2.7 release of the Discovery Environment, all metadata both from within the Discovery Environment (DE) and via iCommands was written to and accessed from the iRODS metadata database. However, the iRODS metadata database allows only three fields (A, V, and U), so it is not ideally suited for the dense data needs of semantic data (e.g., metadata linked to ontology terms).
As a result, CyVerse launched the CyVerse metadata database with the 2.7 DE release. This new database can store an unlimited number of metadata fields, providing a much more scalable framework for the needs of semantic data used in the CyVerse Data Store. Metadata created in the DE after the 2.7 release is stored in the new CyVerse metadata database.
Metadata created before the 2.7 release as part of a DOI request) was already stored in and remains in the DE metadata database.(e.g., SRA submission or
Metadata that was created before the 2.7 release without a template remains safely stored in the iRODS metadata database. That metadata can still be read within the DE, and both written read using iCommands imeta. Users can transfer their data from the iRODS metadata database to the CyVerse metadata database but because it is no longer possible to create iRODS metadata from within the DE, the operation cannot be undone. User who require command-line access to metadata should continue to use iCommands until command-lines access to the DE metadata database is available.
Both databases are indexed, searchable, and accessible through the DE.
Metadata is defined in this system as a triplet (Attribute-Value-Unit):
Attribute Name (AttName)
Attribute Value (AttVal)
Attribute Unit (AttUnits)