new system successfully tested:

Hello you out there!

I just started running the first serious test of the system I’ve developed during this year’s Google Summer of Code. If I wanted to put it in sensational words, the test could be called “Distribution of Particle Physics High Performance Computing Jobs among Multiple Computing Clouds”; just to get some readers :-) . During the test, there will be some time I just sit around and watch my monitor, so I decided to share my experience about the new system with you and keep record of the test progress within this blog post.
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CernVM: local ATLAS Software -- the clean solution

In my blog post CernVM: how to set up a local ATLAS Software Release, I presented a brutal approach how to override CVMFS (CernVM‘s filesystem with HTTP backend) to install a local ATLAS Software release. Now I worked out a very clean and smooth solution. This approach allows:

  • to use the local ATLAS Software without “hacking” anything
  • to use local software and software provided by CVMFS at the same time.


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ATLAS Software: How to run The Full Chain

During development, a system running ATLAS Software has to be tested and validated. There are some standard tests that almost don’t need any input data, stress the system and — if they run properly — are a (very) good indicator that everything is set up correctly. I talk about the so-called JobTransforms. By combining these JobTransforms, the so-called Full Chain can be run — a convenient test. In this blog post I summarize what’s behind the Full Chain and provide a shell script to easily run it.
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EC2: Install ATLAS Software to an EBS volume

In CernVM: local ATLAS Software — the clean solution I proposed to install an ATLAS Software release to an EBS volume. I did it to make it locally available in CernVM running on EC2. The approach allows to move an EBS volume from one EC2 instance to another without losing important components and functionality. Here are some hints (both, CernVM specific and general) to follow before installing the software via pacman.
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CernVM: how to set up a local ATLAS Software Release (dirty version)

One of the main features of CernVM is its special filesystem CVMFS with http backend (based on FUSE). Using CernVM in the standard way, the different experiment softwares work out-of-the-box and are made accessible over the web via CVMFS. Although this is a great feature, I like to set up an ATLAS Software release locally — as real offline version — to be independent of the software-providing webservers.
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Problems at Boston University's ATLAS Software mirror

While installing an ATLAS Software release from Boston University’s mirror, I discovered a broken archive file. It was the fault of a bad network card. The mirror had to be rebuilt from scratch.
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CernVM on Nimbus: kernel problems

In the past days I tried to set up CernVM on a Nimbus cloud to get an ATLAS Software Release (local version) running. On this way some problems came up. One of them could be solved by instructing the Xen hypervisor to choose the proper Linux kernel.
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Resize ext3 file system in loopback file

CernVM for Xen comes as loopback file, containing an Ext3 file system of about 9 GB size, whereas about 8.5 GB are free. Using this free space I tried to set up an Offline ATLAS Software Release (15.1.0). But the filesystem ran full and pacman aborted the setup. The goal is to deploy Virtual Machines of this image within the Nimbus Cloud, which currently does not support additional partitions.

So I had to increase the size of the image / loopback file and to extend the filesystem afterwards. Therefore I basically used dd and resize2fs.
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