At the ORNL DAAC there are currently over 200 datasets, some with as many as 9000 granules each for a total of over 60,000 granules. New datasets continue to arrive daily. Instead, the databases consist of metadata describing the data and its location. Metadata for the data archived at the ORNL DAAC is stored in several Sybase databases. The databases are identical in structure but differ in content.
Metadata progresses through the system of databases as it is ready.
Small tabular datasets are stored on-line on spinning disk. The location of the data is transparent to the user in that the user does not know where the data is stored. The near-line data storage system uses smart staging so the access time varies from seconds to minutes depending upon when that data was last accessed. It can be negligible enough that the data appears to be on-line. For off-line data the user is given a different set of delivery options.