CODA Graham Heyes Computer Center Director Data Acquisition Support group leader

About CODA Common DAQ system at Jlab Designed to be: –Extensible. –Modular. –High speed. –Tailored for Nuclear Physics DAQ. Supported by JLab staff. Design driven by Jlab requirements.

GlueX requirements Rates: –Event rate at L1 ~ 200KHz –Event size at L1 ~ 5 Kbytes ~ 1GByte/S off the detector. –~ 15 to 20 KHz after L3 ~ 100MBy/S to storage.

CODA ~2003 Current front-end hardware –Motorola PPC processors. –Hall B ~ 20 Readout Controllers in parallel. – Highest event rate ~ 10KHz –Highest data rate ~ 20MByte/S to disk. Event Builder –Switched Gigabit ethernet. –UNIX (solaris or Linux) Multithreaded on SMP hardware.

Limitations Hardware interrupt or polling limits event rate. Depends on CPU speed and architecture. Network protocol efficiency limits event transfer rate. Throughput of event builder and speed of disk drives limits throughput to disk.

Solutions Trigger rate too high for per-event readout –Read blocks of events Requires hardware tagging with event identifier (number). 1KHz block rate for 100 events per block is similar to current rates in halls A/B/C. Data rate too high for single data link or CPU. –Parallel readout at front end. > 20 readout controllers can handle 1 Gbyte/S from detector. –Parallel event builder. –Number of event builders depends on technology: > 10 EB for current 1GBit/S networks. –Parallel streams in online L3 farm.

Readout Controller Read blocks from detector at ~ 1KHz. Reformat data blocks into events. Arrange events into blocks for transmission. Transmit event blocks to Event Builders. –Use ET system to transfer data. –ET handles load balance and fault tolerance.

Control and Monitoring Current control system for CODA is slow and hard to maintain. New control system, written in Java for portability is being written. New system will incorporate a “slow control” system. –New system will integrate with EPICS. –Easier to use than EPICS. –Designed for rapid design and prototyping. –Use industry recognized communication standards. –Will allow CODA to “compete” with lab view and other integrated DAQ software.

Summary Rates can be handled by existing technology. Task gets easier and requires less hardware as technology advances. Problem areas: –Storage is not advancing as rapidly as required. –L3 farm needs to be there close to startup.