European SOHO Archive at RAL

SOHO data is archived at GSFC on magnetic disks. PI's in GSFC have ready access to the data. There is also WWW access to the catalogue. WWW access to the data from outside is also planned - but there are stringent conditions on access rights for data files. User authentication is by means of a username and password. The master password database is kept at GSFC and changes must be made by users accessing GSFC.

There is an agreement that the SOHO data, catalogues and corresponding data access database and authentication database will be sent to RAL on a regular basis, in agreed formats.

The following is sent to RAL:

• Ingestion & storage of data:

  FITS files in tar files on DAT-2 tapes are send by mail to RAL from GSFC on a regular basis.

  The tapes are read at RAL and collections of files of about 200MB are written to "virtual tapes" on the ACS. A limited amount of the header is read and recorded in order to identify each file. A catalogue of file identification, virtual tape name and file number is built up.

  Many "virtual tapes" make up one real tape in the ACS. So another catalogue, internal to the ACS system, is built up of virtual tape against real tape position.

  The cat. of file ID and virtual tape info is taken into the SOHO server system.

  Software is also transferred and archived (TBD)

• Ingestion of metadata: The updates to the SOHO catalogue are sent electronically every day and complete copies are sent once a month to ensure synchronisation.

• Ingestion of data access restrictions: The authentication is deposited by GSFC staff on a designated machine at RAl using ftp. The data is encrypted using PGP (To be confirmed).

• Data Access: Users can browse the SOHO catalogue via the WWW. Users may also identify themselves and then query which files they have read access to. A selection of these files may then be requested. The user gives a machine name, account and password to enable the SOHO server to ftp the files to the requestor.

• Data Dissemination: The archive server receives the request. It then performs the following steps:
  • checks the authentication and data access rights for the requested files,
  • looks up the virtual tape and file number for each file,
  • makes a request to the ACS to transfer these files - unless they are in the cache,
  • writes the files to cache disk and records the existence in cache,
  • initiates the ftp transfer to the user.

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