Data Management. Machine / Application State Data. Outline. EPICS Archiver Gathering related datasets File vs. database storage. EPICS Archiver. EPICS toolkit does provide an archiver > 100,000 different signals are archived at SNS (various rates)
Machine / Application State Data
Gathering related datasets
File vs. database storage
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
Is beam loss related to cooling temperature?
Great for seeing what failed first
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
What were all the magnets in a beamline set to at 11:23:01 AM on 05/11/2008 ?
CSS – Powerful archive -viewer
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
Services are headless executables (no GUI)
Run continuously in the background
Typically on one instance runs
Sometimes more than one instance can run across servers
Provides remote communication with user interfaces
XAL defines an API for communication between client and service
Uses open standards
XML-RPC for communication
mDNS for dynamic service discovery
It will grab a prescribed set of PVs as a collection
Can prescribe a collection rate
Can trigger on demand a set
e.g. when a beam measurement is done
Can define many independent sets of data to log
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)
In order to restore the state of a machine, need to capture all settable values in the beamline
Magnet fields, RF amplitude/phases, foil poisition, timing setup, …
Need to monitor readback values for these devices
A power supply could be tripped
Need convenient restore mechanism
Need convenient browsing of save-sets
Viewable comments helpful
Useful for Physics Application Setup Information
What sequence is used, what range is being scanned, plot configurations, etc.
Can be used for data storage as well
XML data format is used in XAL
Easy to create hierarchal storage
Typically this type configuration is managed in the “document” part of the application (document – view – control architecture model)