CTA Schema

Here is CTA schema:

Unlike Enstore schema, the CTA db schema is more normalized and specifically separates out the concepts of logical libraries, virtual organization, storage class into corresponding tables. Therefore, the names of virtual_organization, logical_library and storage_class have to be defined by admin in advance before any file can be written.

Additionally CTA has a concept of tape_pool that represents logical grouping of tapes. Each tape belongs to exactly one tape pool. Tape pools are used to keep data belonging to different VOs, storage_class (via archive_route).

The archive_route table connects storage_class to tape_pool and specifies how many copies a file must have.

File table

CTA separates the concept of file into an abstract archive_file that may have multiple corresponding tape_file entries. The archive_file table stores file size; adler32 checksum; disk instance name; disk_file_id - an inode number on storage front end; unique file id (archive_file_id); user UID/GID and a deleted flag.

A tape_file references archive_file and contains information that ties it to the tape - like volume id (vid); location on the tape and copy number.

Storage class table

The storage class concept is somewhat similar to file family concept of Enstore. Besides unique name storage_class_name it specifies how many copes a file must have. And it has a reference to virtual_organization.