ALICE bags data storage accolades

ComputerWorld has recognized CERN with an award for the 'Best Practices in Storage' for ALICE's data acquisition system, in the category of 'Systems Implementation'. The award was presented to the ALICE DAQ team on 18 April at a ceremony in San Diego, CA.

Between 16 and19 April, one thousand people from data storage networks around the world gathered to attend the biannual Storage Networking World Conference. Twenty-five companies and organizations were celebrated as finalists, and five of those were given honorary awards-among them CERN, which tied for first place in the category of Systems Implementation for the success of the ALICE Data Acquisition System.

CERN was one of five finalists in this category, which recognizes the winning facility for 'the successful design, implementation and management of an interoperable environment'. 'Successful' could include documentation of a positive impact of the facility on other organizations, the reliability and efficiency of the facility's data-sharing procedure, and the integration of the system with other systems or departments in the organization. 'It was a big surprise to me that we won the award,' said ALICE physicist Ulrich Fuchs. 'We had strong competitors.' Among the finalists were Brookhaven National Lab, Stanford University, and NBC New York. The award-choosing procedure was very competitive indeed: for the first time in the history of the prize, the awards committee came up with two honorees for a single category, when all their usual selection criteria resulted in a tie between CERN and Stanford University.

The ALICE DAQ team developed their system in order to buffer up to eight hours of data on their own. This required a 'randomization of traffic': instead of reading and writing to disks linearly-the most efficient way-the data had to be accessed in a randomized way, which caused the team to lose 90 per cent of their performance value. 'Simply everybody would tell you it was impossible to read and write more than two gigabytes per second in random patterns,' Fuchs said.

To solve the problem, the ALICE DAQ team used storage software provided by Quantum Corp. to separate the two data streams to different discs, turning what would have been randomized traffic into a linear recording. Using this method, they exceeded their goal of 2.5 GB/sec-the same rate as roughly 84 million mobile phone calls per second-and completed a successful data challenge run, working with three other teams at CERN to generate and store one petabyte of data in just 18 days. (See Bulletin No. 8/07)