Access to tape devices in MIDAS

A more complete description of how MIDAS accesses tape devices can be found in the chapters Tape Devices in MIDAS and Tapeserver Installation.

In MIDAS, tape devices are accessed via the INTAPE/OUTTAPE commands. They accept logical and system devicenames for tape devices.

• Access to tape devices via logical names
  Logical names for tape devices start with the string tape (case insensitive) and must be defined in the environment. Example:

  Midas 003> $echo $tape0
  ws7:/dev/nrst1
  (or just /dev/nrst1 if the tape device is located in localhost)
  Midas 003> INTAPE/FITS 1-10 aaa tape0

  When first started, MIDAS appends to the environment all definitions found in the configuration file /midas/98NOV/monit/devices.sh. You will have to edit this file to assign the system names for your tape devices hostname:devicename to the logical names tapename, and must follow the next convention:

  set tapename=hostname:devicename ; export tapename # comments

  where:

  tapename

  is the logical name used by INTAPE/OUTTAPE commands. The name must start with the prefix tape (lower case) to be considered a tape device.

  hostname

  is the official name of the host to which the device tape is attached to.
  NOTE: alias hostnames are not recognized. Official name is printed by the command hostname.

  devicename

  is the system device name for the tape in its not_rewind_mode. On many Unix systems, the not_rewind_mode is selected for those tape devices names with the prefix character: n.
  NOTE: The MIDAS tape interface will not work properly with the rewind_mode name.

  The character : is the separator between hostname and devicename. An example for the file devices.sh could look like:

   
      set tape0=ns0:/dev/nrst0 ; export tape0  # here_some_comments
      set tape8mm=ns2:/dev/nrst2 ; export tape8mm # here_some_comments
  

  Also the comments for each logical tape definition (anything after the # character) can be used later for the generation of the help file /midas/98NOV/prim/help/tapede.alq (used by the MIDAS command HELP [TAPEDEVICES]) if they follow the next convention:

      #:tape_type:capacity_density:location
  

  where:

  tape_type

  stands for the type of the tape (maximum of 9 characters). E.g.: DAT/DDS, 8mm, QIC-24.

  capacity_density

  stands for the capacity or density of the tape (maximum 9 characters). E.g.: 1.2Gb, 8Gb, 6250 bpi.

  location

  stands for the physical location of the tape device (maximum 16 characters). E.g.: User room 2nd floor, room num. 443.

  The MIDAS help file /midas/98NOV/prim/help/tapede.alq is generated by executing the following:

  % cd /midas/98NOV/prim/help
  % make tapede.alq
  

  An entry in the file devices.sh like:

      set tape0=ns0:/dev/nrst0 ; export tape0  #:DAT/DDS:1.2Gb:Tape room
  

  will generate an entry in the help file tapede.alq like:

     Name      Host      Device         Tape      Cap/Den   Location
     tape0     ns0       /dev/nrst0     DAT/DDS   1.2Gb     Tape room
  

• Access to tape devices via system names
  System devicenames for tape devices can also be used directly in the INTAPE/OUTTAPE command line. The syntax must be devicename if the tape device is located in localhost, or hostname:devicename if the tape device is located in a remote host As described above devicename is the system device name for the tape in its not_rewind_mode. Example:

  Midas 003> INTAPE/FITS 1-10 aaa ws7:/dev/nrst1
  (or if the tape device is located in localhost)
  Midas 003> INTAPE/FITS 1-10 aaa /dev/nrst1