An Overview of PHENIX Computing

Ju Hwan Kang (Yonsei Univ.) and

Jysoo Lee (KISTI)

International HEP DataGrid Workshop November 8 ~ 9, 2002

Kyungpook National University, Daegu, Korea

RHIC

Configurations: Two concentric superconducting magnet rings (3.8Km circumference) with 6 interaction regions

Ion Beams: Au + Au (or p + A) s = 200 GeV/nucleon luminosity = 21026 cm-2 s-1

Polarized proton: p + p s = 500 GeV luminosity = 1.4 1031 cm-2 s-1

Experiments: PHENIX, STAR, PHOBOS, BRAHMS

PHENIX Experiment

Physics Goals Search for Quark-Gluon Plasma Hard Scattering Processes Spin Physics

Experimental Appratus PHENIX Central Arms (e, , hadrons) PHENIX Muon Arms ( )

PHENIX Data Size

Peak DAQ bandwidth in PHENIX is 20 MB/sec.

Ion Beams (Au + Au) 1. Minimum bias events (0.16 MB/event): Raw event rate = 1400 Hz (224 MB/sec) Trigger rate = 124 Hz (20 MB/sec) 2. Central events (0.4MB/event): Trigger rate = 50 Hz (20 MB/sec)

Polarized proton (p + p) All events (25 KB/event):

Raw event rate = 250 KHz (6250 MB/sec) Trigger rate = 800 Hz (20 MB/sec)

RCF

RHIC Computing Facility (RCF) provides computing facilities for four RHIC experiments (PHENIX, STAR, PHOBOS, BRAHMS).

Typically RCF gets ~ 30 MB/sec (or a few TB/day) from the PHENIX counting house only through Gigabit network. Thus RCF is required to have complicated data storage and data handling systems.

RCF has established an AFS cell for sharing files with remote institutions and NFS is the primary means through which data is made available to the users at the RCF.

The similar facility is established at RIKEN (CC-J) as a regional computing center for PHENIX.

Compact but effective system is also installed at Yonsei.

PHENIX Computing Environment

Linux OS with ROOT PHOOL (PHenix Object Oriented Library):C++ class library (PHOOL) based on top of ROOT GNU build system

LocalDisks

Database

Reconstruction Farm

Calibrations&

Run Info

RawData

DSTData

BigDisk

HPSS

Mining&

Staging

AnalysisJobs

Tag DB

CountingHouse

PrettyBigDisk

RawData

Data Carousel using HPSS

To handle annual volume of 500TB from PHENIX only, High Performance Storage System (HPSS) is used as Hierarchical Storage system with tape robotics and disk system.

IBM computer (AIX4.2) organizes the request of users to retrieve data without chaos.

PHENIX used ten 9840 and eight 9940 drives from STK.

The tape media costs about $1/GB.

“ORNL”software

carouselserver

mySQLdatabase

filelist

HPSStape

HPSScache

pftprmine0x client

pftp CAS

data mover

CAS local disk

NFS disk

Data carousel architecture

Disk Storage at RCF

The storage resources are provided by a group of SUN NFS servers with 60TB of SAN based RAID arrays backed by a series of StorageTek tape libraries managed by HPSS.

Vendors of storage disks are Data Direct, MTI, ZZYZX, and LSI.

Linux Farms at RCF

CRS (Central Reconstruction Server) farms are dedicated to the processing of raw event data to generate reconstructed events (strictly batch systems without being available for general users).

CAS (Central Analysis Server) farms are dedicated to the analysis of the reconstructed events (mix of interactive and batch systems).

The LSF, the Load Sharing Facility, manages batch jobs.

There are about 600 machines (dual CPU, IGB memory, 30GB local disks) at RCF and about 200 machines are allocated for PHENIX.

offline software technology

analysis framework C++ class library (PHOOL) based on top of ROOT

base class for analysis modules• “tree” structure for holding, organizing data

can contain raw data, DSTs, transient results• uses ROOT I/O

database using Objectivity OODB for calibration data, file catalog, run info, etc.

expecting ~100 GB/year of calibration data

code development environment based heavily on GNU tools (autoconf, automake, libtool)

PHENIX CC-J

The PHENIX CC-J at RIKEN is intended to serve as the main site of computing for PHENIX simulations, a regional Asia computing center for PHENIX, and as a center for SPIN physics analysis.

Network switches required to connect HPSS servers, the SMP data servers, and the CPU farms at RCF.

In order to exchange data between RCF and CC-J, a proper bandwidth of the WAN between RCF and CC-J is required.

CC-J has CPU farms of 10K SPECint95, tape storage of 100 TB, disk storage of 15 TB, tape I/O of 100 MB/sec, disk I/O of 600MB/sec, and 6 SUN SMP data server units.

Comparable mirror image into Yonsei by “Explicit” copy of the remote system

Usage of the local cluster machines Similar operation environment (same OS, and similar hardware spec) 1. Disk sharing through NFS One installation of analysis library and sharing by other machines 2. Easy upgrade and management

Local clustering Unlimited network resources between the cluster machines by using 100Mbps (No NFS lagging and instant X-display as an example) Current number of the cluster machines = 2 (2CPUs) + 2 (as RAID)

File transfers from RCF Software update by copying shared libraries (once/week, takes less than about 1 hour) Raw data copy using “scp” or BBFTP (~1GB/day)

Situations at YONSEI

Yonsei Computing Resources

Yonsei Linux boxes for PHENIX analysis use

4 desktop boxes in a firewall (Pentium III/IV) Linux (RedHat 7.3, Kernel 2.4.18-3, GCC 2.95.3) ROOT(ROOT 3.01/05)

One machine has all software required for PHENIX analysis Event generation, reconstruction, analysis Remaining desktops share one library directory with the same kerne

l and compiler etc… via NFS 2 large RAID disk box with several IDE HDDs (~500G X 2) and several small disks (total ~500G) in 2 desktops Compact but effective system for small user group

Yonsei Computing Resources Linux (RedHat 7.3, Kernel 2.4.18-3 ,GCC 2.95.3) ROOT(ROOT 3.01/05)

Database

Reconstruction

Calibrations&

Run Info

RawData & DST

Big Disk(480G X 2)RAID tools for Linux

AnalysisJobs

Tag DB

Gateway

Library(NFS)OBJY

P4 2G480G DISK

P3 1G

P3 1G

P4 1.3G480G RAID DISK

Firewall

100Mbps

PHENIX Library