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Grid - FAQ
Introduction and Overview
What is a Grid?
A Grid is a aggregation of several, single computer which are connected. A software controls the aggregation and distributes tasks (=jobs) at the Grid, this means to the single computers.
What can a Grid?
The specialty of a Grid is, that by the aggregation of several computer much greater computing jobs can done. This is very beneficial in contrast to classical mainframes.
The Grid of the RWTH Aachen University provides a infrastructure which make it possible to offer computing power.
This based on mutuality.
So, it is very important that a lot of people use the Condor client on their computer, to achieve high computing power.
How does a Grid work?
The functioning of a Grid is the following: On the one hand hand the computer are connected physically (Local Area Network or Internet), on the other hand the Grid software is responsible for the controlling. The main part of this software run on one ore more central computers and is responsible for the distribution of the jobs to the connected computers, which have free capacities.
Before a user can submit a job, the job must be made "grid-able" by the user (Adjust the job to the new working situation). Then the job can be submitted to the Grid software which is responsible for the execution of the job.
Condor als Gridsoftware
There are a lot of different software packages to control a Grid. The RWTH-Grid uses the software Condor, a Grid software which is available for a lot of different operating systems and architectures. Condor consists of a small software which runs on every computer, this software is responsible for acceptance of jobs and on the other hand Condor has a central manager which coordinates the Grid.
The Condor-Grid at the RWTH Aachen University
The main goal of the RWTH Grid is to provide as much computing capacity as possible for members of the RWTH Aachen University without additional costs. For this done by the installation of the Condor client on a lot of computers (Students, employees of institutes and facilities and CIP pools). If the client is installed, the computer is switched on, is connected to the network of the RWTH Aachen University and is not used it is connected to the Condor server.
The condor server is operated by the Center for Computing and Communication. This server is responsible for the distribution of jobs to the unused computers. It is also possible that members of the RWTH Aachen University submit jobs to the server.
For this the Center for Computing and Communication made a selection of "grid-able" and often used software, which normally needs a lot of computing time and which use the Grid reasonable. The software selection is extend every time.
Condor Server
Function
The Condor server has a central role at the RWTH Grid. The server is responsible for the authentication of the users and computers, acceptance of jobs and the notification if job are finished. The server also supervises the Grid and the execution of jobs.
Zugang
The access to the Condor server is done via the web interface, the address of the interface is: https://rwth-grid.rz.rwth-aachen.de/.
For accessing the Grid an ID in our user administration (TIM) is necessary!
If you already have a user ID and a password, this is the ID you use for dial-in services or for your email address, you have the required ID. If you do not have such an ID you can use the following form to apply an ID.
Applications
At the item "Submit jobs" you can find all available applications. With the adequate, additional parameters and the input data a job can be started. If applications are missing, please contact the Grid group. They can integrate the application.
Filemanager
The filemanger administrates the different data of the applications. You have to upload the input files for a job into the upload directory, this contains directories for the different applications. If a job is finished you will find the results in the directory "Results" at the directory of the application.
Condor Client
Function
The Condor client is responsible for the connection of the computer to the RWTH Grid. If the computer is unused, the client is responsible for the notifivation of the server that free resources are available. Then the server can assign a job to the computer.
Installation
You can download the Condor client here. After the launch of the installation file, the client will be downloaded automatically. After the installation is finished you have to logon to the Condor server and download a individual configuration file via the filemanager. Copy this file to C:\Programme\Condor\
Condor via VPN with Linux
By default, the Condor software uses the first network interface. It is possible to assign the network interface via the configuration file (NETWORK_INTERFACE = ip-address), but this does not work with dynamic IP addresses. The only solution is to define the right network interface at first. This is done with the following command:
/sbin/ifconfig cipsec0 | fgrep "inet " | awk -F: '{print $2}' | awk '{print $1}'
Misc
Certificates
The connection to the Grid server is done vis https. For the verification the browser need the following certificate: Certificate of the RWTH-CA.
Help / Questions
If you have further question, comments please send an email to: grid@rz.rwth-aachen.de