1. Remote Online Farms TDAQ Sander Klous ACAT 2007 25 April
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vrijdag 28 december 2018
Remote Online Farms 01 11
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1110
11001
01011
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Sander Klous
On behalf of the
Remote Online Farms
Working Group
TDAQ
ACAT 2007
25 April W H  t Z
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2. Large Hadron Collider and ATLAS
Pos429.ppt
Large Hadron Collider and ATLAS
vrijdag 28 december 2018
The experiments in the Large Hadron Collider in general, and ATLAS in particular, need to solve yet another problem.
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3. Data processing nightmare
Pos429.ppt
vrijdag 28 december 2018
There is no way to store all the info produced by ATLAS
40 million events per second x 1.5 MB/event = 60 TB per second
In fact: % of the data is thrown away
So… The data processing nightmare is all about storage
Unfortunately… No
Rigorous multilevel trigger system
First level in hardware
Higher levels in software
But what if your favorite channel is not in the %?
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4. Online bottleneck Well, that’s a problem… Scarce CPU resources
Pos429.ppt
Online bottleneck
vrijdag 28 december 2018
Well, that’s a problem…
Scarce CPU resources
Physics events are selected on inclusive signatures
High energy leptons, missing ET, high pT jets, etc.
Resources assignment must be balanced carefully
So… the data processing nightmare is all about CPU
No! Sorry, but there is more to it…
LVL1
HLT
So… The data processing nightmare is all about CPU
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5. Some are more equal than others…
Pos429.ppt
vrijdag 28 december 2018
Some are more equal than others…
Physics selection
Networking enables us to
prioritize these activities
So…
The data processing nightmare is all about networking
Detector calibration
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6. Economics Computing grid In fact, it is about balance
Pos429.ppt
vrijdag 28 december 2018
Data Acquisition
40 MHz
Level 1
Level 2
Accept 1 in 500
Accept 1 in 50
Accept 1 in 10
Level 3
In fact, it is about balance
Maximize performance  Minimize costs
Amsterdam
NIKHEF/SARA
Network
switch
Computing grid
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7. Gary Stix, editor of Scientific American
Pos429.ppt
Is it worth the effort?
vrijdag 28 december 2018
January 2001
Gary Stix, editor of Scientific American
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8. This can be difficult… The basics
Pos429.ppt
vrijdag 28 december 2018
This can be difficult… The basics
Copenhagen
Edmonton
Krakow
Manchester
Amsterdam
North Area ATLAS Detectors
Level 1 Trigger
Remote Event Processing Farms
ROB
ROB
ROB
ROB RF RF
Data Collection Network RF RF
SFI
SFI
SFI
Packet
Switched
(GEANT)
Back End Network
lightpath
L2PU
Event Filter EF
SFO
Bdlg. 513
Mass
storage
Switch
Local Farm
The “Magni” Cluster
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9. Stream implementation
Pos429.ppt
vrijdag 28 december 2018
Stream implementation
Remote
Stream n
Stream 1
Stream 2
From LVL1
(Partial) Event
LVL1 Info
RoutingTag
StreamTag
(Partial) Event
LVL1 Info
RoutingTag
StreamTag 1
Event
LVL1 Info
RoutingTag
StreamTag 2
Ath / CALid
Ath / PESA PT
Event
LVL1 Info
LVL2
SFO
RoiB
Ros/Robin
pRos
Stream
selection
Add to
StreamTag1
Event
LVL1 Info
RoutingTag
StreamTag 2
EFD
(Partial) Event
LVL1 Info
RoutingTag
StreamTag 1
L2sv
Input
Create
RoutingTag
Routing
DFM B
L2pu
ExtPT
SFI (partially) build
Ath / CalStr
Ath / CALIB PT
Add to
RoutingTag
Routing
Create
StreamTag D C
Trash
ExtPT
Add to
StreamTag2
Duplicating
Output
Output
Stripping
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10. Grid/Proxy implementation
Pos429.ppt
Grid/Proxy implementation
vrijdag 28 december 2018
SFI UI
SFI
SFI
Broker
EFD
Dispatcher
Buffer
EFD
Buffer
Proxy PT
Infrastructure
monitoring
HEP VO
Database PT PT PT PT PT PT
int.eu.grid HEP VO
Application
Monitoring
Local PT Farm CE PT PT CE
Events
Remote PTs
Worker Nodes
Worker Nodes
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11. Pos429.ppt
vrijdag 28 december 2018
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12. Pos429.ppt
vrijdag 28 december 2018
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13. Open issues Data management Software management Database access
Pos429.ppt
Open issues
vrijdag 28 december 2018
Data management
Software management
Database access
Authentication, Authorization and Accounting
Performance and reliability
Looking for PhD student…
If you are interested:
Mail to
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14. Conclusion Remote online farms are interesting
Pos429.ppt
Conclusion
vrijdag 28 december 2018
Remote online farms are interesting
From a physics perspective
From a computer science perspective
From an organizational perspective
Infrastructure is put in place
Many open questions
More news next year
PhD candidates: mail to
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