Transcript Data Management Machine / Application State Data 5/24/2016 J-PARC

Data Management
Machine / Application State Data
5/24/2016
J-PARC
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Outline
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EPICS Archiver
Gathering related datasets
File vs. database storage
EPICS Archiver
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EPICS toolkit does provide an archiver
> 100,000 different signals are archived at SNS (various rates)
Great for looking for unanticipated correlations between different
effects
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Great for seeing what failed first
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Is beam loss related to cooling temperature?
Uses the time of arrival to the archiver as the time-stamp
Not good for fine-scale time resolution (< 1 sec)
Cumbersome to gather collected sets of large amounts of data
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What were all the magnets in a beamline set to at 11:23:01 AM on
05/11/2008 ?
EPICS Archive Viewer
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CSS – Powerful
archive -viewer
Collected Data Set Storage
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Why Bother ?
Often applications do not work in the control room
when connected to live data for the first time.
It is useful to have a “beam replay” mode for
diagnosing application problems after a beam shift (i.e.
the next day after you’ve slept some).
When analyzing beam behavior at some moment, it is
useful to know the value of all the magnets / BPM
readings at that time – difficult to do with the Archiver
XAL Services – A Digression
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Services are headless executables (no GUI)
Run continuously in the background
Typically on one instance runs
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Sometimes more than one instance can run across servers
Provides remote communication with user
interfaces
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XAL defines an API for communication between client
and service
Uses open standards
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XML-RPC for communication
mDNS for dynamic service discovery
PV-Logger Service
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It will grab a prescribed set of PVs as a collection
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Can prescribe a collection rate
Can trigger on demand a set
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e.g. when a beam measurement is done
Can define many independent sets of data to log
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These definition sets are defined in a database
Data sets are stored in a database
Allows easy browsing
Other tools can access these sets (e.g. Online Model)
Machine Save – Compare-Restore
(SCORE)
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In order to restore the state of a machine, need to
capture all settable values in the beamline
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Need to monitor readback values for these devices
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Magnet fields, RF amplitude/phases, foil poisition, timing
setup, …
A power supply could be tripped
Need convenient restore mechanism
Need convenient browsing of save-sets
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Viewable comments helpful
Data Storage: File vs. Database
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File Storage
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Pros
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Cons
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Easy to implement
Can readily get you hands on the information (editor)
Problem archiving
Not easy to browse contents of many files
Database
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Pros
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Cons
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June 16-27, 2008
Easy management of old data
Wealth of query tools available
More trouble for the initial deployment
USPAS
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File Data Storage
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Useful for Physics Application Setup Information
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Can be used for data storage as well
XML data format is used in XAL
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What sequence is used, what range is being scanned, plot
configurations, etc.
See gov.sns.tools.xml.samples
Easy to create hierarchal storage
Typically this type configuration is managed in the
“document” part of the application (document – view –
control architecture model)