The FATMEN file catalogue retains minimal information about tapes upon which data reside. It assumes that full details are kept in a Tape Management System (TMS), with which the file catalogue is fully integrated. When a user wishes to access a dataset on a given tape or cartridge, the FATMEN system will inquire of the TMS whether the user has the required access permission, whether the media is in fact available, its location etc. Using the information returned, it will then build a valid tape STAGE request, specifying the device type required and other details such as label type (ASCII, EBCDIC, Unlabelled). Thus, users need not know that their data resides on a tape which is in an automatic loader, or indeed if it is on tape at all!
When a new dataset is created, the TMS may also be used to allocate a new tape or cartridge within a certain storage group as specified by the user. The TMS provides a great deal of flexibility in this area, thus an experimental group may divide up its tape allocation into separate pools for raw data, Monte Carlo data, DSTs and other data. The user may then request a tape from the appropriate storage pool, or provide a user routine to perform the allocation.
The CERN TMS resides on CERNVM. All access to the TMS is via the SYSREQ communications package. Remote access is provided via a TCP/IP server into CERNVM, called TCPREQ. The user may issue TMS commands without passing through the FATMEN system: these will typically be performed by the tape librarian or group tape managers. More details of the TMS are given in a separate document: The CERN Tape Management System (to be published).
Remote sites with their own TMS's are required to provide two FORTRAN interface routines to link their TMS to the FATMEN system. An interface already exists for VMTAPE and is selected with the PATCHY flag
+USE,VMTAPE.
The following restrictions apply if the FATMEN file catalogue is used without a TMS: