1. DAQ software for SND detector
Budker Institute of Nuclear Physics, Novosibirsk
M. Achasov, A. Bogdanchikov, A. Kim, A. Korol

2. VEPP-2000 collider In the past: SND @ VEPP-2M Today: SND @ VEPP-2000
Years:
Energy (2E): 0.36 – 1.4 GeV
Today:
VEPP-2000
Project started: 2000
Energy: GeV
Luminosity: (2 GeV)
Perimeter: 24.4 m
Collision time: 82 nsec
Beam current: 0.2 A
Bunch length: 3.3 cm
Energy spread: 0.7 MeV
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

3. VEPP-2000 collider ACAT05, Zeuthen January 11, 2019 Session 1,
SND DAQ software

4. SND DAQ requirements
Loose electronic selection conditions (FLT), strong software (TLT) filtration (ratio to 10%).
Readout process should work on the stand-alone equipment, separately from processes which consume a lot of computational power (TLT).
Event selection using fully reconstructed events – L3 farm.
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

5. Readout and events building
Main data flow
100 Hz
1 KB
1 kHz
4 KB
1 kHz
4 KB
1 kHz
1 KB
Readout and events building
Events packing
Events filtering
Storage
Expected rates:
Events fragments: 4 МB/s are read from IO processors over Ethernet;
Event building: 4 MB/s;
Event packing: 1 МB/s;
Events filtering (90% screening): 100 KB/sec.
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

6. Raw events transfer (alternatives)
Readout L3
Sum
Storage L3 L3
Readout L3
Storage
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

7. Raw events transfer (software layers)
Abstract layer
Container capture
Read events from container
Write events to container
System layer
Global File System (GFS) – tested
Shared raw disks
Network File System (NFS)
Hardware layer
Shared SCSI disk - tested
Network disk
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

8. DAQ architecture Detecto r Front-end electronics Off-line
Filtered events
Backup
X 16
X 12
KLUKVA
CAMAC
TLT computers
Visualization
Readout & Event Building
Buffer
Database
Calibration process
System support
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

9. Main online processes Events treatment : Control :
Readout & event building
Scalers (statistics from electronic subsystems)
L3 (packing, reconstruction, filtration, statistics)
Calibration on events
Control :
Operator interface
Distributed processes management
Context recovery after process crash
Informer (message analyzer)
Electronics sub-system control
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

10. Readout process state machine
Auto-start
Idle
Monitoring
Readout
Pause
Configuration
Initialization
Start
Reject
Full stop
Stop
Success
Note: error branches are not shown, all errors cause Idle state.
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

11. Process starter service
Database
TLT1
Process A: 2
Process B: 1
Process C: 3
TLT2
Process A: 1
Process D: 3
Online Computer TLT1
Online Computer TLT2
Starter service
Starter service
Process A
Process D
Process A
child
Process B
Process C
Process A
Process D
Process A
Process C
OK, one session ID
needs to stop
Process C
Process D
needs to start
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

12. Processes states and recovery
After start processes should receive domain name from “domain distributor server“ (DD). Each domain contains fixed name variable to store a path to recover program. When process crashes (tears connection), DD starts recover program with domain name as parameter.
Current process state data are stored in the OnlState database and may be accessed by other processes.
State variable type: int, float, string, arrays;
access index: domain_name/variable_name
Atomic domain access.
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

13. Process context recovery
Domain states:
Free
Context recovery
Busy
Confirmation
Domain request
Process finished
Process crashed
Distributor server crashed and restarted
Start recovery program
Confirmation timeout
Re-register domain
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

14. } Online Databases Online state DB Conditions DB Configurations DB
Bookkeeping DB }
Closely tiered. To simplify access integrated interface is supported.
Implementation: RDBMS (MySQL)
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

15. Configurations & Bookkeeping API
Table description (SQL format)
table.sql
parser
C++ description and implementation
table.h table.cc
Application
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

16. Operator interface Run control Web-log Database access Process control
Communication
Personal settings
Status
Selective views
Run conditions
Occupied resources
Users contacts
User info
Start Stop Pause
Message search
Configurations
Processes start list
Chat
UI details
Message add UI
Calibrations
UI colors
Silence
Extended messages
notifications
Statistics
Scalers selection
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

17. Operator interface components
HTTP server
Configurations PHP API
Calibrations PHP API
Online States PHP API
PHP scripts
Recovery PHP API
Web-log PHP API
HTML
javascript
RDBMS
Configurations API
Calibrations API
Online States API
Online Process
Recovery API
Web-log API
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

18. Web-log messages
The web-log toolkit consists of several interfaces written in languages PHP and C ++, which allow to choose, add and expect the message.
Each message has attributes:
Alarm – is on when required to draw attention of the operator immediately.
Date and time of the message.
Topic of the message (what field it belongs to).
Severity of the message (fatal mistake, error, warning, info, debug, trace).
Sender: user, host, process name.
Subject – the summary of the message. This is a basic field.
Message attachments of any MIME-type. Full description of the problem, pictures, diagrams can be presented in the attachment. Attachment has attributes: name, size and inline. The attribute inline is a recommendation for browsers, whether to include attachment in the message directly or display just a link.
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

19. Statistics view (example)
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

20. Design High level robustness: raw events deep buffering;
High quality of filtering: full events reconstruction before filtering;
Reuse of off-line framework software;
Relational databases to store experiment configurations, states, calibrations;
Operator interface: web technologies .
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software

21. Status DAQ system software status:
Event transfer mechanism were tested on the maximum possible rates;
The most important functionality were realized;
Advanced features were added;
: system were used to receive events from the drift chamber prototype.
ACAT05, Zeuthen
January 11, 2019
Session 1,
SND DAQ software