= Hints for using the Cray-XC30 at HLRN =

* Running remote jobs 
* Fortran issues

== Running remote jobs ==

Starting from r1255,  PALM allows full remote access of the Berlin complex of HLRNIII. Since the batch compute nodes do not allow to use ssh/scp (which is required by '''mrun''' for carrying out several crucial tasks, e.g. for automatic submission of restart runs), the ssh/scp commands are executed on one of the login nodes (blogin1) as a workaround. Therefore, blogin1 must be a known host for ssh/scp. This requires the user to carry out the following three steps just once:

   1. Login on blogin and create a pair of private/public ssh-keys (replace <hlrn-username> by your HLRN-username):
{{{
      ssh <hlrn-username>@blogin1.hlrn.de
      ssh-keygen -t dsa
}}}
      Enter <return> for any query, until the shell-prompt appears again.

   2. On blogin, define the public key as one of the authorized keys to access the system:
{{{
      cat  id_dsa.pub  >>  authorized_keys
}}}
   3. Still logged in on blogin, login on blogin1:
{{{
      ssh <hlrn-username>@blogin1
}}}
   After the third step, the message
{{{
Warning: Permanently added 'blogin1,130.73.233.1' (RSA) to the list of known hosts.
}}}
   should appear on the terminal.


== Fortran issues ==

The Cray Fortran Compiler (ftn) on HLRNIII is known to be less flexible when it comes to the Fortran code style. In the following you find known issues observed at HLRNIII.


=== NAMELIST files ===
* It is no longer allowed to use a space character between the variable name of an array (e.g. {{{mask_x_loop}}}) and the bracket "{{{(}}}".\\'''Example:'''\\{{{mask_x_loop (1,:) = 0., 500. ,50.,}}} (old)\\{{{mask_x_loop(1,:) = 0., 500. ,50.,}}} (new).

=== Conditional statements (IF-THEN-ELSE) ===
* It is no longer possible to use {{{==}}} or {{{.EQ.}}} for comparison of variables of type LOGICAL.\\'''Example:'''\\{{{IF ( variable == .TRUE. ) THEN}}} is not supported. You must use {{{IF ( variable ) THEN}}} (or {{{IF ( .NOT. variable ) THEN}}}) instead.