Difference between revisions of "Online Design Goals"
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* Rate to local raid disk - 100 MByte/sec (100 MByte/sec) | * Rate to local raid disk - 100 MByte/sec (100 MByte/sec) | ||
* Rate to silo - 100 MByte/sec (100 MByte/sec) | * Rate to silo - 100 MByte/sec (100 MByte/sec) | ||
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| + | The goals above refer specifically to the trigger and DAQ systems. Most other online and controls systems have no specific rate requirements. Event monitoring at low luminosity requires enough events to fill histograms reasonably quickly, perhaps a few thousand events/second (a few times 5 MByte/sec) to the prototype L3 farm. | ||
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| + | ==Timelines== | ||
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| + | First beam to the hall is expected in ????. Prototype versions | ||
Revision as of 10:01, 24 July 2007
Overview
Below I list the overall performance requirements and design goals of Hall D DAQ/Online/Control systems. All groups working on the project, e.g. JLab DAQ group, JLab Electronics group, etc, must design to meet them.
The JLab DAQ group will develop a similar document, then the two will be reconciled and dates, performance milestones, etc. will be developed. We will repeat this with other JLab groups as needed.
Basic Requirements from Hall D Design Report
At turn-on Hall D will accept 10**7 photons/sec, with an expected trigger rate of 18 kHz, assuming a L1 rejection rate of 50%. At high luminosity the beam rate will be ten times higher, or 10**8 photons/sec, giving an expected trigger rate of 180 kHz assuming the same L1 rejection rate. If the events average 5 kByte then the data rate off the detector at low luminosity will be 90 MByte/sec, and 900 MByte/sec at high luminosity. At low luminosity there will be no L3 rejection, and all events will be written to disk (at 90 MByte/sec). At high luminosity we expect a L3 rejection rate of a factor of 10, so the rate to disk will also be 90 MByte/sec.
Design Goals
The DAQ design must have a little headroom above the expected rates, and the initial design must meet the requirements of high luminosity. Thus I propose the following design goals (numbers in parenthesis are for low luminosity):
- Trigger rate - 200 kHz (20 kHz)
- Typical event size - 5 kByte (5 kByte)
- Data rate off detector - 1 GByte/sec (100 MByte/sec)
- Rate to L3 farm - 1 GByte/sec (no requirement for rate to prototype farm)
- L3 rejection - factor of 10 (no rejection)
- Rate to local raid disk - 100 MByte/sec (100 MByte/sec)
- Rate to silo - 100 MByte/sec (100 MByte/sec)
The goals above refer specifically to the trigger and DAQ systems. Most other online and controls systems have no specific rate requirements. Event monitoring at low luminosity requires enough events to fill histograms reasonably quickly, perhaps a few thousand events/second (a few times 5 MByte/sec) to the prototype L3 farm.
Timelines
First beam to the hall is expected in ????. Prototype versions
