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BESIII computing. 王贻芳. Peak Data volume/year. Peak data rate at 3000 Hz Events/year: 1*10 10 Total data of BESIII is about 2*640 TB. BESIII computing needs. CPU power Storage Network System software. CPU power needed for data reconstruction and simulation. - PowerPoint PPT Presentation
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Peak Data volume/year
• Peak data rate at 3000 Hz
• Events/year: 1*1010
• Total data of BESIII is about 2*640 TB
Event size(KB) Data volume(TB)
RAW 12 120
REC. 24 240
DST 2 20
MC-Rec 24 240
MC-DST 2 20
Total 640
CPU power needed for data reconstruction and simulation
• Four times reconstructions/year• Equivalent to a farm of 200 P4 1.6G• Analysis needs another farm of 100 P4 1.6 G • Maybe underestimated
MIPS/event Events (1010)
Total CPU (MIPS)
Event reconstruction
20 4 40,000
MC simulation 200 1 100,000
MC reconstruction
20 4 40,000
Total 180,000
Data type and storage media
• Store 3 reconstructions
• Virtual storage library
• Fast and automatic access
Data type Data volume(TB) device
Raw 240 Tape lib.
Rec 1440 Tape lib.
DST 120 Disk array
MC-Rec 1440 Tape lib. ?
MC-DST 120 Disk array
Tape reading/writing speed
• Online data recording(writing):
3000*12KB=36MBytes/s
• Reconstruction(reading/writing):
3000*24KB*5*2 = 760MBytes/s
• MC simulation ?
3000*24*2 = 152MBytes/s
It is almost impossible ! We should design our software framework carefully to minimize the data size !
Disk read/write access speed
• Data Reconstruction
3000*2KB*5 = 30 MB/s
• MC simulation
3000*2KB*5 = 30 MB/s
• Analysis
40*40Mb = 200 MB/s
main building to computer center
Network needs• From Online farm to computer center
3000*12KB = 36 MB/s
A dedicated Gbps network line for safety and stability
• Offline farm
network a bottleneck
• User analysis
> 40 users access disk files
Software system
• Mainly based on free software
• CERN library based
• Following latest development of HEP software