No. 52 (00164)

Family name : Adachi
Given name : Ichiro
Affiliation : High Energy Accelerator Research Organization
Abbreviation : KEK
E-mail address : ichiro.adachi@kek.jp
Title : The Belle computing system
Authors : I.Adachi, R.Itoh, N.Katayama, T.Tsukamoto, T.Hibino,
M.Yokoyama 
Abstract : 
We present the present status of the computing system in the Belle
experiment at the KEKB e+e- asymmetric-energy collider. So far, we have
logged more than 150 fb$^{-1}$ of data, corresponding to the world
largest data sample of 150M $B\bar{B}$ pairs at the $\Upsilon(4S)$
energy region.  This is a challenging issuse for event processing as
well as for data storage system, and to get physics results in a timely
manner from such a large data, efficient usage of CPU and careful
control of data storage for user analyses has to be considered.

To process a huge amount of beam data, a computing farm consisting of
one thousand CPUs has been introduced, in which 90(300) quad(dual) CPU
PC servers from multiple vendors, as the core processing system, have
been effectively used.  The processed beam data have been recorded in an
array of the hard disks mounted to the disk servers. To reduce data
size, new data format has been employed and all file information have
been kept in our database to control users' access as easily as
possible.

he details of this computing system and performance of data processing
will be demonstrated. Then, from our experience, a possible computing
model for future high luminosity experiment with more than 10^{35}$
cm$^{-2}$sec$^{-1}$ will be discussed.