Difference between revisions of "Online Design Goals"
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==Overview== | ==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. | + | Below I list the overall specifications, 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. | 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. | ||
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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. | 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. | ||
| − | Online and controls systems must be capable of configuring, monitoring, and controlling: approximately | + | Online and controls systems must be capable of configuring, monitoring, and controlling: approximately 80 front-end crates; a few hundred detector control points, where e.g. a HV control point may include hundreds of actual channels; a few dozen compute servers; L3 farm consisting of up to 200 nodes; a 10-GBit networking system; many hundreds of alarm channels; monitoring and bookkeeping for triggering at 200 kHz, data taking at 100 MByte/sec, and runs lasting from a few minutes to a few hours; ... |
Revision as of 10:40, 24 July 2007
Contents
Overview
Below I list the overall specifications, 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
The Hall D DAQ will be composed of approximately 80 front-end synchronous crates; a much smaller number of asynchronous data sources; and a few dozen other software components that do not generate high-speed data, but need to be integrated into the run control system.
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.
Online and controls systems must be capable of configuring, monitoring, and controlling: approximately 80 front-end crates; a few hundred detector control points, where e.g. a HV control point may include hundreds of actual channels; a few dozen compute servers; L3 farm consisting of up to 200 nodes; a 10-GBit networking system; many hundreds of alarm channels; monitoring and bookkeeping for triggering at 200 kHz, data taking at 100 MByte/sec, and runs lasting from a few minutes to a few hours; ...
DAQ Design Goals
The initial design must meet the requirements of high luminosity with the exception of the L3 farm, which at turn-on will be a small prototype, used for monitoring only. Note that at high luminosity events will be written from the L3 farm to disk, while at low luminosity they will be written from an earlier stage. Also note that during installation and testing the trigger and DAQ software must be capable of supporting multiple, simultaneous runs to allow detector groups to check out their hardware in parallel.
The DAQ design must include some headroom above the expected rates. Thus I propose the following design goals and parameters for the Hall D DAQ (numbers in parenthesis are for low luminosity):
- Physics trigger rate - 400 kHz (40 kHz)
- L1 rejection rate - 50% (50%)
- Accepted 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 (20 MByte/sec at turn-on to prototype farm for monitoring)
- L3 rejection - factor of 10 (no rejection)
- Rate to local raid disk - 100 MByte/sec from L3 farm (100 MByte/sec from earlier stage)
- Rate to silo - 100 MByte/sec (100 MByte/sec)
Note that all other online and controls systems have no specific rate requirements.
DAQ Timelines
First beam to the hall is expected in ????, with production data taking expected to start in ????. Prototype DAQ systems for individual detector testing must be available by ????. The full DAQ must be ready for testing the complete detector with cosmic or pulser triggers by ????.
