Certain features of the FATMEN system may be reconfigured at run-time, both via the FORTRAN callable interface or interactive shell. A description of what can be tailored is given below.
The FATMEN software attempts to determine various information, such as the current host name and account, by calling system routines. In some cases, it may be desirable to override the values returned. This can be done by setting variables (environmental variables in Unix, global symbols in VAX/VMS).
For example, the SHIFT facility at CERN is composed of a number of systems (shift1, shd01 etc.). By default, a file created on a given system would not be accessible on another as the node name check would fail. To override this, the variable FMHOST is set, as below.
setenv FMHOST shift
The account field can be set in a similar way, e.g.
FMACNT:==JDSCT
for a VAX/VMS system.
If FATMEN has been installed using the TMS flag, media attributes are obtained from the TMS (Tape Management System). (A preliminary interface to the VMTAPE package also exists and is selected via the flag VMTAPE).
On other systems, the defaults can be overridden globally, or on a per volume basis. Ideally, the media attributes for a given site should be automatically selected via installation flags. However, the FMEDIA callable routine and MEDIA shell command permit the default values to be overridden at any time.
For example, to change the generic device name of media type 2, which defaults at CERN to CT1, the following command could be used.
MEDIA 2 3480 TA90
By default, all entries in the FATMEN catalogue are visible and may be examined using the shell command ls. One may limit the range of entries that can be seen by defining a list of location codes, copy levels and media types. These lists also affect those files that may be accessed, and the selection procedure itself.
For example, an experiment which computes at several laboratories will probably have copies of the tapes containing the DST information at each site. The shell command
set/location 1-3
would prevent any catalogue entries with a location code outside the range 1-3 from being visible. This is particularly useful for large collaborations that typically have many copies of each dataset.
It is also important to set the correct range for efficiency in data access. In the case where an experiment has multiple copies of a file on different tapes, each at a different laboratory, FATMEN will normally issue a TMS query for each volume to see if it is accessible. Setting the location code correctly reduces the number of TMS queries and hence improves data access time.
In the case of the location code or copy level, only those entries with a value in the defined range will be visible or accessible. In the case of the medium type, the order of the values is also important. By default, FATMEN first looks for a disk file, then a copy on a 3480 cartridge and so on. The shell command
set/media 5,1,2
would cause FATMEN to first look for a copy on an Exabyte 8500 cartridge, then disk and finally a 3480 cassette, assuming the default medium attributes.