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).

   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.