HOWTO: Start using the grid
A quickstart tutorial

by Silvia D. Olabarriaga (silvia@science.uva.nl)
edited by Dennis H. van Dok (dennisvd@nikhef.nl)

Introduction

This HOWTO document outlines the necessary steps to get access the grid resources offered by the VL-e Proof-Of-Concept environment. Although it is particularly tailored for vlemed, it is generally applicable for all wannabee grid users.

This is a step-by-step guide to get pole position on the grid. You can follow this guide blindly, which will be the fastest way to get started, but if get confused and/or need more details, you can always select "Show more info" to get in-depth background information, explanations, and references to relevant websites.

See? This text just became visible because you selected the above link. If you didn't see the link and didn't do anything, that's ok too—it just means that javascript support is disabled and all the extra information is visible by default.

If javascript works, the link functions as a toggle. The purpose of all this is merely to keep the view from becoming cluttered by a lot of complex and potentially confusing information. So maybe you'd be better off without reading all the extras, in case you become even more befuddled!

see also The PoC website. under Infrastructure: Authentication Central facilities R0

NOTE: some of the steps can take a few days, since they require manual processing.

The steps outlined below should be followed in linear order, except steps 2a, 2b and 2c which can be done in parallel.

  1. Obtain a grid certificate
    1. Get an SRB account
    2. Register with the VleMed organisation
    3. Get an account at the SARA User interface
  3. Configure account at the UI
  4. Run your first job on the grid.

Step 1: Obtain a grid certificate

A grid certificate is a “passport” for using grid resources.

Are you sure you want to be reading this paragraph? I explained in the previous “extra info” block that it may do more harm than good. So unless you absolutely, definitely, really need to know everything about grid certificates you should probably skip this section.

A grid certificate is a personal electronic document that testifies your true identity, much like a passport. Lets see how they compare.

Before the CA can sign your certificate, your true identity has to be checked. That means that you will have to

Identity checking and signing is done with mathematical sorcery called public key cryptography. The gist of it is that someone holding the public key of your certificate can challenge you to prove your identity by asking a question that only the holder of the private key is able to answer. To prevent identity theft, you should never hand over your private key to anyone, not even to the CA.

Digital signing is the other way around: your certificate is signed vith the CA's private key. The CA's public key can be used to ‘decrypt’ the signature to verify that

  1. the signature matches your certificate and
  2. the signature was made by the CA.

Since the CA's certificate is publicly available, anyone can check the validity of your certificate.

Even more information:

Get a grid certificate from the DutchGrid certificate authority, by going to http://www.dutchgrid.nl/ca/request/ and filling out the web form:

You'll will be asked to follow a sequence of steps including

IMPORTANT: your private key will be stored in the file "userkey.pem". There are three golden rules:

After your request has been processed, you'll have to "install" your certificate in all computers that you use to access the grid. This means that a directory called ".globus" will have to be copied into your home in all the computers you'll be using to access grid resources.

This directory contains essentially 2 files:
userkey.pem
the private key generated by the script above
usercert.pem
file received by e-mail when your certificate is approved by the Certification Authority (CA).
Important: the access properties of these files are very important, but sometimes they are affected by ftp. They should look like this: 
$ ls -la ~/.globus/user*
-rw-r--r--    1 silvia   silvia       6659 Feb 15 11:53 usercert.pem
-r--------    1 silvia   silvia        963 Feb 13 14:37 userkey.pem
(which means that no one can read the private key file other than the owner.) The best is to use zip or tar to copy the complete ".globus" directory into the computers you'll use. see also

Step 2a: Obtain account on SRB

To get an SRB account, send mail to grid.support@sara.nl.

The request will be processed manually and confirmed via e-mail. you'll get an e-mail containing your user name and a password.

You can later change the password with a command-line utility (Spasswd) See also below Configuring your account at the UI.

instructions about how to access the files is given in http://poc.vl-e.nl/srb/

Step 2b: Register with the VleMedical VO

This is necessary to associate your certificate to one "virtual organization" (= group of people that have access to shared grid resources). To register, follow the instructions on http://register.matrix.sara.nl/. Indicate VO (virtual organization) = VleMedical.

You'll get back an e-mail confirming your registration to the grid and VO.

You may think that this step is superfluous after having gone through all the trouble getting a grid certificate. But you should realise that while a certificate helps to establish your identity, it does not give you the rights to use any resources. Those rights are usually handed down through virtual organisations, and that is why you need to register your affiliation.

As part of this step you need to load your certificate into your browser. Here is another page explaining how.

Step 2c: Obtain account at SARA user interface

Step 3: Configuring your account at the UI

This machine has all the environment necessary to access grid resources.

Step 4: Running your first job on the grid

General instructions for running jobs

Advanced

my proxy template of JDL file (for Glue=PoC, time, etc) rubjob.tz