Experimental Physics and Industrial Control System (EPICS) Archiver

1
Experimental Physics and Industrial Control
System (EPICS)Archiver

• Bob Dalesio, May 19, 1999

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Data Archiving

• Channel Archiver is used to save channels at a
  set interval or on change. Each channel can be
  saved at a different frequency. This approach is
  most efficient for selecting an arbitrary set of
  channels and viewing them through time.
• Save Set Archiver is used to save sets of
  channels at the same time. This is most efficient
  for calling up a set of values for a single time.
  Applications include warm reboot files and
  restore files for resetting setpoints or
  maintaining counters through a reboot.

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Archiving
Time/Data Viewer
Data Set Viewer
Analysis
CDEV Service Library
Channel Retrieval Library
Save Set Retrieval Library
Status Display
Status Display
Channel Archiver
Save Set Archiver
Channel Access Client Library
Channel Access
Archive Record
Any Field
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Channel Archiver Configuration - Defaults/Global
Parameters

• at the beggining of the line - this is a
  comment
• !write_freq ltsecondsgt write buffers to disk at
  this rate
• !save_default ltsecondsgt default rate to put
  channel into buffer
• !file_size lthoursgt time before
  creating a new file
• !display_size ltchannelsgt number of channels
  before going to set
• !get_threshold ltsecondsgt save times greater
  than this use ca_get
• !group ltfilenamegt include this
  configuration file

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Channel Archiver Configuration - Channel
Specification

• ltchannelgt archive at default_frequency
• ltchannelgt ltsecondsgt archive every ltsecondsgt
• ltchannelgt Monitor ltsecondsgt archive every
  change
• ltchannelgt Disable archive at deafult_frequency
• disable archiving when not zero
• The circular buffer needs to be big enough to
  hold the fastest rate of change. Set ltsecondsgt to
  the fastest rate the channel may change. Achiving
  channel data on change can fill lots of disk
  space!

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Channel Archiver - Operation

• Start the channel archiver by typing
  freq_arch config file name ltdirectory file
  namegt
• A graphical user interface appears.
• Archived data is saved in the directory from
  which the program is invoked.
• During operation, new configuration files can be
  included and archive frequencies can be changed.
• Positive feedback is given through the user
  interface.
• 2,000 updates per second has been demonstrated
  either having 200 channels update at 10 Hz or
  2,000 channels updated at 1 Hz on an IPC.
  Measurements needed for the Ultra1. Goal is to
  archive 20K samples per second on the Ultra.
• Stopping and restarting the archiver, using the
  same directory name will append the new data to
  this data archive.
• Multiple copes can run in multiple directories or
  on multiple machines - but not to the same
  directory!
• Operational at LEDA and in beta test at several
  other sites.

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Save Set Archiver - Configuration

• !frequency ltsecondsgt save the set at this
  interval
• !monitor save the set when any channel
  changes
• !mon_frequency ltsecondsgt if using monitor - max
  rate is ltsecondsgt
• !group config_file include this
  configurationfile
• !reboot ltngt keep ltngt ascii
  versions of the save set
• !nobinary do not produce successive binary
  sets
• !named_files save ascii file into name file
• !warm_time minutes if save set older than
  this - do not restore
• channel include this channel in the set
• channel Monitor save the set when this
  channel changes
• channel Filename use this channel for the
  name
• The user interface also allows for manual save
  of each set

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Channel Archive Data Retrieval

• freq_retriever - creates several text reports of
  the data
• freq_table - creates a tables with columns for
  channels and rows for time stamps
• beta use of xarr - graphical plotting program for
  channel data.
• Retrieval times are a function of the number of
  files being accessed. The default file time is 24
  hours.
• Tests run on retrieving 1,024 samples from 110
  files extracted data into the local buffer in 3
  seconds on a Sparc IPC writing to a remote disk
  on a Sparc 10. One files data is returned in
  around 100 msecs.

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Save Set Archive Retrieval

• ss_get - creates several reports
• Reboot files are saved in ASCII and can be viewed
  with any text tool
• Save set files are saved in ASCII and can be
  viewed with any test editor
• No plotting support yet
• dbrestore used to restore save sets created with
  this program using the database access library.
• LEDA RF is restoring named save sets during
  operation with a channel access client
  application.

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Comments...

• Data management is being started..
• The use of a realtional database for initially
  storing data or as a long term repository for
  data is being studied.
• The lack of a client/server based run time viewer
  makes the verification of operation possible only
  from the machine on which the archivers are
  started.
• The lack of a server on the archive data requires
  that the viewer be running on a machine that has
  the archive data mounted.
• A minimum set of tools for save/restoring and
  viewing archive data is available as a
  preliminary release.
• Kay Kasemir (and hopefully Chris Larrieu) will
  talk about the work being done to complete the
  archive tool.