Computing : NAF Login, WGS and remote Desktop

The NAF is reachable via ssh, through an internet browser ssh interface and through Jupyter notebooks.

For access to the NAF, you need a DESY user account and the correct resources assigned to you. Please ask your group leader and your namespace administrator for the necessary capabilities.

ssh Access

Login is possible from outside the DESY network with a ssh client.

Simply connect to a cluster of work group servers (WGS) with

ssh account@naf-YOURGROUP.desy.de 

where naf-YOURGROUP.desy.de is the WGS address of your group listed below. You should use the generic name (e.g. naf-YOURGROUP.desy.de) instead of a particular server name (e.g. naf-YOURGROUP11.desy.de) in general, since we balance the load and availability behind the generic name.

Browser Access & Remote Desktop:

Point your browser to one of our generic systems:

• https://naf-x-el.desy.de:3389 ... currently, an CentOS 7 system
• https://naf-x-ubuntu.desy.de:3389 ... currently, an Ubuntu 20.04 system

You can also use a dedicated client if you make much use of FastX, please contact naf-helpdesk@desy.de for more information.

See below for more information on the configuration and usage of these systems.

Jupyter Hub

Jupyter provides interactive notebooks based on Python. Please check the dedicated documentation on how to use Jupyter notebooks on the NAF.

Usage of WGS

Be reasonable when you use the WGS as you are sharing the resources with your colleagues and any (mis)use will affect them. So, please be careful and nice to your colleagues. As a rule of thumb, use the WGS for development, short (<10min) test jobs, graphical things, ... Do not use the WGS for longer lasting processes, or processes that do not require interactive return. Such processes are best placed onto the batch system - which has much more resources and resource control mechanisms.

We check WGS on a daily basis, and if we find long running jobs or jobs consuming huge amounts of memory, we write an automated email.

We have to reboot systems to activate new kernels. Using load balancing and alias mechanisms, we try hard to keep logins alive for at least one week. Sometimes we must act faster, though.

NAF Work-Group-Server WGS

Usually, you will login via ssh to a WGS (work group server). Usually, one or more WGS exists per experiment. HTCondor is available on all nodes for submission into the NAF/BIRD

Other Work-Group-Server WGS with access to BIRD batch system

(Operating system: EL7 = CentOS 7 - for other operating system please consider using Singularity containers on the NAF)

Grid Commands

The generic Grid commands are not automatically set up on the WGS' but can be easily sourced:

naf-xxx: [~] source /cvmfs/grid.desy.de/etc/profile.d/grid-ui-env.sh
Using Grid environment in '/cvmfs/grid.cern.ch/centos7-umd4-ui-4_200423'.
Adding DESY site environment.

NAF Remote Desktop

You can run graphics application on the NAF by logging in like the following: ssh -X user@naf-wgs.desy.de This works ... but the X-protocol is not good at handling latency. Whereas this will work sufficiently fast and fluid when you log in from a DESY Hamburg machine (be it your desktop or your laptop), a login from DESY Zeuthen or CERN will result in a much slower work even if the bandwidth is sufficiently large. This is even worse when you log in from your home computer via DSL or from a mobile device.

A possible alternative is the usage of a protocol that hides the latency. NX-like protocols and tools can do this, but they need client and server programs.

Our idea is to give NAF users working from remote access to a machine acting as "a desktop at DESY" via such an NX-like protocol. This desktop can then be used to perform the ssh -X user@naf-wgs.desy.de necessary to run the graphics application.

The product used is the FastX  product from Starnet.

Here you see an example usage. The left part shows how a remote user would run graphical application on a WGS, whereas the right part shows a Hamburg user.

Access: 

Point your browser to one of our generic systems:

• https://naf-x-el.desy.de:3389 ... currently, an CentOS 7 system
• https://naf-x-ubuntu.desy.de:3389 ... currently, an Ubuntu 20.04 system

You can also use a dedicated client if you make much use of FastX, please contact naf-helpdesk@desy.de for more information.