His group’s second objective is to port applications to a wide range of platforms. This is because using multiple platforms has proved an invaluable way of debugging programs — bugs show up on some platforms and not on others — and to prepare the code to be ported to new technologies when they emerge.

Physicists in the ALICE team also need good quality office and presentation capabilities. CERN scientists need to share knowledge and communicate their findings effectively with funding authorities and research institutions throughout the world.

“Many of our people find they carry around dual-boot laptop PCs with two operating systems — one running UNIX or LINUX for their analysis work, and the other with Windows”, explains Carminati.

Effective development

The ALICE computing group implemented a mini cluster of 8 nodes of Apple Xserve and Xserve Raid dual processors, and ported both the software environment and the grid software — including the common LCG MiddleWare and the ALICE specific requirement. Since Apple began to deliver Macs with Intel chips, the improved performance has persuaded the group to double the cluster.

We use multimedia a great deal. It is not the first parameter of platform choice, but given the choice between a Mac and a system with comparable performance, our people will choose the Mac because of the added multimedia value.

— Federico Carminati, ALICE Computing Coordinator

“We have nearly 1600 Mac users at CERN. Since we took delivery of a number of laptops with Intel chips the performance improvements have been phenomenal”, says Fons Rademakers, ALICE Offline Computing Software Architect. “On the older Macs, compiling code took one and a half hours. With the new ones we are down to 10 minutes. So Apple is now an extremely effective development environment and we know it is likely to be very cost effective”.

The Macs also provide the kind of high quality multimedia presentation and conferencing capabilities required by the ALICE team’s scientists. “We use multimedia a great deal”, says Federico Carminati. “It is not the first parameter of platform choice, but it’s great that you have that on the Mac, as well as the UNIX environment. Given the choice between a Mac and a system with comparable performance, our people will choose the Mac because of the added multimedia value”.

Main engine

The benchmark results are likely to give Apple technology a significant role in the success of the ALICE experiment — both within CERN and at the grid computing centres. According to Federico Carminati: “Most of our core team of 15 or so developers here at CERN are using LINUX-based platforms, but if our tests continue to be positive, we will buy more Intel-based Macs and they will become a main computational engine”.

Once a ‘farm’ of Intel-based Macs has been installed at CERN, it is likely that other computer centres will send representatives to assess the results. “We know that a number of centres would like to run Macs”, says Rademakers, “but if we weren’t running our infrastructure on the platform, they could never make the move. Now they can”.