In the HTCondor pool at CNAF are currently installed 4 ARM worker-nodes, they are configured to accept jobs both via local (on sn-02) or Grid submission (e.g. ce02-htc).

UI-ARM

Login to ui-arm

A new user-interface has been installed to let users test and submit jobs developed for ARM CPU architecture. Please find below all the instruction to log into ui-arm.cr.cnaf.infn.it.

1. ui-arm should be accessed by users only from their usual user-interface to prevent any issues (for the sake of this tutorial ui-tier1 will be the one of choice). Do not access ui-arm from the bastion host even though it seems to be working.
   As a first step, a user should have generated a pair of ssh-keys on the usual user interface (e.g. ui-tier1.cr.cnaf.infn.it).

   SSH-Key Generation

   In case no ssh-keys are present into ~/.ssh/ directory, a new one can be generate executing the ssh-keygen command

   [apascolini@ui-tier1 ~]$ ls -la ~/.ssh
   total 17
   drwx------  2 apascolini cms  512 Feb  1 15:33 .
   drwxr-x--- 19 apascolini cms 8192 Feb  1 15:33 ..
   
   [apascolini@ui-tier1 ~]$ ssh-keygen
   Generating public/private rsa key pair.
   Enter file in which to save the key (/home/CMS/apascolini/.ssh/id_rsa): <press_enter>
   Enter passphrase (empty for no passphrase): <insert_passphrase/press_enter>
   Enter same passphrase again: <insert_passphrase/press_enter>
   Your identification has been saved in /home/CMS/apascolini/.ssh/id_rsa.
   Your public key has been saved in /home/CMS/apascolini/.ssh/id_rsa.pub.
   The key fingerprint is:
   SHA256:fWCSzY0p7W1afvPMgGNtQORJXRV/9Jb6pm8LAnqGNK4 apascolini@ui-tier1.cr.cnaf.infn.it
   The key's randomart image is:
   +---[RSA 2048]----+
   |            o. o*|
   |         = B ...+|
   |        + O =  .=|
   |         * +  ...|
   |       oS.o *.   |
   |      o + .* +.  |
   |       + o..=.*o |
   |      . o  ..++B |
   |     E       .oo=|
   +----[SHA256]-----+
   
   [apascolini@ui-tier1 ~]$ ls -la ~/.ssh
   total 17
   drwx------  2 apascolini cms  512 Feb  1 15:34 .
   drwxr-x--- 19 apascolini cms 8192 Feb  1 15:33 ..
   -rw-------  1 apascolini cms 1679 Feb  1 15:34 id_rsa
   -rw-------  1 apascolini cms  417 Feb  1 15:34 id_rsa.pub

   
   

2. Once both the public and private keys are present in the ~/.ssh directory, the user can enable ssh access to ui-arm via ssh-key, by appending the content of the ~/.ssh/id_rsa.pub file into the ~/.ssh/authorized_keys file

   [apascolini@ui-tier1 ~]$ cd ~/.ssh
   
   [apascolini@ui-tier1 .ssh]$ cat id_rsa.pub >> authorized_keys
   
   [apascolini@ui-tier1 .ssh]$ ls -la
   total 42
   drwx------  2 apascolini cms  512 Feb  1 15:42 .
   drwxr-x--- 19 apascolini cms 8192 Feb  1 15:33 ..
   -rw-------  1 apascolini cms  417 Feb  1 15:41 authorized_keys
   -rw-------  1 apascolini cms 1679 Feb  1 15:34 id_rsa
   -rw-------  1 apascolini cms  417 Feb  1 15:34 id_rsa.pub

3. After these steps the user is now able to access ui-arm via ssh with the same user used to log into the previous user-interface

   [apascolini@ui-tier1 ~]$ ssh ui-arm
   
   Warning: Permanently added 'ui-arm,131.154.192.208' (ECDSA) to the list of known hosts.
    ___ _   _ _____ _   _        ____ _   _    _    _____
   |_ _| \ | |  ___| \ | |      / ___| \ | |  / \  |  ___|
    | ||  \| | |_  |  \| |_____| |   |  \| | / _ \ | |_
    | || |\  |  _| | |\  |_____| |___| |\  |/ ___ \|  _|
   |___|_| \_|_|   |_| \_|      \____|_| \_/_/   \_\_|
   
   Welcome to ui-arm.cr.cnaf.infn.it - AlmaLinux 9.3
    This node is under the control of Puppet 7.27.0
   
    Kernel: Linux 5.14.0
   ----------------------------------------------------------
   
   Last login: Wed Jan 31 16:50:35 2024 from 131.154.193.196
   [apascolini@ui-arm ~]$

Once on ui-arm

This user-interface has a minimal configuration, compared to other UIs, due to many software/services not being compiled on this kind of architecture. 

Please find below all the features supported on the UI.

In case a user needs other packages (compiled for aarch64) to be available on ui-arm, can contact the user-support team.

Submitting on ARM worker-nodes

Local Jobs

To submit local jobs to ARM wn no additional configuration is needed. A user can submit directly on sn-02 as described in HTCondor jobs - Submit local job.

Grid Jobs

In case of Grid jobs the cluster is configured to redirect to ARM nodes all jobs containing the attribute WantARM = True. Please find below few examples of grid jobs submitted both via VOMS proxies or SciTokens.

# Unix submit description file
# sleep.sub -- simple sleep job
  
use_x509userproxy = true
+owner = undefined
+WantARM = True

executable              = sleep.sh
log                     = sleep.log
output                  = outfile.txt
error                   = errors.txt
should_transfer_files   = Yes
when_to_transfer_output = ON_EXIT
queue

# Unix submit description file
# sleep.sub -- simple sleep job
  
scitokens_file = $ENV(HOME)/token
+owner = undefined
+WantARM = True

executable              = sleep.sh
log                     = sleep.log
output                  = outfile.txt
error                   = errors.txt
should_transfer_files   = Yes
when_to_transfer_output = ON_EXIT
queue

Any further information on how to submit grid jobs can be found in HTCondor jobs - Submit grid job.