Tape interface in MIDAS

MIDAS users read and write their data by using two well-known MIDAS commands called INTAPE/OUTTAPE that read and write user data in FITS and IHAP formats. The new version of these two commands used in MIDAS are able to access data files both on disk and on tape. The argument for the input/output device (prefix) can be the system device-name (e.g /dev/nrst0) or a environment variable starting with the string tape (case insensitive) defining a system device-name, or filenames on disk.

By default, the access to files on disk is included in all releases of MIDAS. It uses the standard file interface common to all Unix systems.

Access to tape devices can differ from one system to another, and, within the same system, not all tape devices are accessed the same way. Drivers for tape devices are depending on the manufacturer implementation (and sometimes they also change with different versions of the OS), however more and more manufacturers are adopting a semi-standard interface called mtio. The standard MIDAS installation provides a generic tape driver based in this interface and therefore is able to handle most tape devices. If this driver is not sufficient for your some of your tape devices you will have to implement your own driver following the procedures indicated in the next sections.