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manuals:bachelorservers

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Servers for bachelor students

Leiden Observatory provides three powerful compute servers that bachelor students will use for their research projects. Each server has 96 CPU cores, 500 GB of internal memory, 50 TB of disk storage, and runs the Linux operating system RedHat version 7. Students are expected to use their own laptop or desktop computer (or possibly some other device) to connect to one of the servers via the internet. This page provides information on how to connect to the servers, and some basic information on how to use them. More general information about the computer environment and the software used by Leiden Observatory can be found here.

Note that students need a Leiden Observatory computer account (which is not the same as an ULCN account) to be able to connect to the servers.

Which bach(elor) server to connect to

The servers are located in a special server room, protected from overheating and power interruptions. User access to these machines is solely through an internet connection. The names of the three servers are:

  • bach1.strw.leidenuniv.nl
  • bach2.strw.leidenuniv.nl
  • bach3.strw.leidenuniv.nl

As the servers are shared by many students, it is best to spread the load between the three servers. Before connecting (see below), one can look which machine has the most resources (free CPUs, memory, disk space) available by going to this webpage. Note that there is a fair use policy in place, meaning that there are no hard limits on how much resources a single user or project can use. However, excessive use will be monitored, and limits may be put in place if excessive use leads to problems for other users. If large shares of resources are required for your project, please discuss this with your supervisor and the Leiden Observatory IT department.

Connecting to the bach servers

All three servers are running xrdp, which is an open source RDP service (RDP = Remote Desktop Protocol by Microsoft). Once you selected a suitable server (bach1, 2 or 3), you can connect to it using an RDP client program. Depending on the operating system on your own device, the RDP client will look and work slightly differently. Below there is some guidance for the most common cases (Windows 10, MacOS, Linux).

When a student connects to a particular server using RDP for the first time, it will start a new desktop session unique for each user (the default lightweight desktop is called MATE). This session can stay active, even when the student disconnects from the session. When the student connects again to the same server, this will reconnect to the same session. This allows for students to continue working on their projects when and where they can, without the hassle of having to close down and restart the required software. This also enables running long computations without the need to having to keep the personal laptop or computer open. Students should keep in mind that disconnected but active sessions still use up some server resources.

Note that it is (in principle) possible to connect to a single session from multiple computers, hence allowing for remote collaborative work. However, do not share your account information (username, password) to give others access to your session! If multiple connections to a single session are required for your project, please discuss this with your supervisor and the Leiden Observatory IT department.

Below is some guidance on how to connect to a server from different operating systems. It is important to know that connections from outside Leiden Observatory need to pass through an additional layer of security. The description below explains how to connect from the outside (which also works at Leiden Observatory) using a technique called ssh tunneling.

Connecting from Windows

Connecting from MacOS

Connecting from Linux

Disconnecting or finishing a session

To keep a session running on the server, just close the window of the RDP client program running on your computer, or disconnect in your Microsoft Remote Desktop window. Next time you connect to the same server, you will re-enter the running session.

If you are done with a session, you can Log out in your session on the server. This will close all open windows and terminate the session. Next time you connect to the same server, a new session will be started.

Storing and accessing your project data

Project data can be stored on one of the three 50 TB disk storages connected to the bach servers (see schematic drawing below). From any of the bach servers (or any Linux computer on the Leiden Observatory network), you can access any of the three storages via the /net/<server>/data2 path, where <server> is the name of the server that the storage is connected to (bach1, bach2, or bach3, without the .strw.leidenuniv.nl part). For example, you can have a session running on bach1 and store/access your data on the storage connected to bach3 using the /net/bach3/data2 path. To keep the data from many users organized, please open a terminal and create a sub-directory with your Leiden Observatory username to store your data in. For example:

mkdir /net/bach3/data2/<username>
cd /net/bach3/data2/<username>
... etc ...

Please note that the data storages connected to the bach servers are not meant for long-term storage. In principle, all data areas will be cleared before next year's bachelor students start. At the end of the project, the students and their supervisors are responsible for copying away any data that needs to be stored long-term, or discuss possible data retention options with the Leiden Observatory IT department.

manuals/bachelorservers.1580894761.txt.gz · Last modified: 2020/02/05 09:26 by intema