What Do I Want from an RDB

1
What Do I Want from an RDB?

• Ned Arnold, APS
• March 9, 2005

2
What do I want?

• To alleviate the guilt when someone mentions
  documentation of the installed control system.
• As-built drawings
• To allow for quick, yet well-documented changes.
• e.g. We need a thermocouple on the septum magnet
  for the next machine studies tomorrow
• To allow for quick, yet well-documented changes
  by a ltcompetentgt substitute staff member.
• e.g. and George isnt here today!
• To provide convenient thorough information for
  fast troubleshooting i.e. helpful documentation
• To provide convenient and thorough information to
  on-call staff for systems for which they are
  unfamiliar.
• I cant talk to the Attenuator in Sector 7
• There is a white box on my medm screen

3
What do I want?

• To make the learning curve of applications less
  steep
• To automate finding the root cause of a
  communication problem
• To run numerous integrity crawlers for constant
  monitoring of the health of the control system
  (self generating?)
• To alleviate the guilt when someone mentions
  documentation of the installed control system.

4
What doesnt work?

• Maintaining accurate information on the thousands
  (15,000) of installed devices and hundreds of
  independent applications is not manageable with a
  Revision Controlled Drawing approach.
• Our control system is not static.
• There are many soft entities that defy
  drawings.
• Different views of the system are needed at
  different times, yielding redundant drawings.
• Drawings cannot be queried.

5
Drawings are not maintainable ltwith our budgetgt
6
What might work? What do we want to document?

• All PV definitions in all the IOCs
• Provides an aggregate collection of the entire
  distributed database

Process Variables
7
What might work? What do we want to document?

• All active IOCs
• IP
• Contact Person
• Ethernet Connections
• Boot path
• etc, etc, etc

IOCs (CASs)
8
What might work? What do we want to document?

• All installed components
• VME /VXI Modules
• Instruments
• Racks
• etc, etc, etc

Components
9
What might work? What do we want to document?
Cables

• All installed cables
• Ambitious, but necessary

10
What might work? What do we want to document?

• Installed Applications
• A ltsomewhat arbitrarygt collection of functions
  (databases, seq programs, etc.) that can be
  identified as a unique application
• LINAC Beam Position Monitors
• Bunch Compressor Scraper
• Storage Ring Injection Kicker PS Control
• SR Vacuum Valve Interlocks

11
What might work? What do we want to document?
Cables
Must document all of these installed entities
and
Components
IOCs (CASs)
Process Variables
12
What might work? What do we want to document?

• and their relationships to one another
• Components are related to other components by
• how they communicate control information
• how they are housed
• how they are powered
• Applications are related to PVs, Components, etc
• IOCs are related to Components, PVs, Applications
• Cables are related to Components (via ports)

13
All entities are inter-related

• Given a Cable, one can determine
• Device, IOC
• PV
• Applications

• Given a IOC, one can determine
• Applications
• Devices
• Cables
• PVs

• Given a PV, one can determine
• Applications
• Devices, IOC
• Cables

14
What can it tell me?

• What process variables are associated with this
  device?
• What process variables were added, changed, or
  removed since the last run?
• Where does the other end of this cable go?
• What components do all of these non-functioning
  devices have in common?
• Which module type in this system has the worst
  reliability history?
• How many devices of a particular model number are
  installed?
• Where are all the devices of a particular model
  number installed?
• What application software will be affected if
  this device is removed?
• What equipment will be affected when this breaker
  is locked-out?

15
What do I get?

• No guilt when someone mentions documentation of
  the installed control system.
• Quick, yet well-documented changes.
• Quick, yet well-documented changes by a
  ltcompetentgt substitute staff member.
• Convenient thorough information for fast
  troubleshooting helpful documentation
• Convenient and thorough information to on-call
  staff for systems for which they are unfamiliar.
• This PV isnt working
• I cant talk to the Attenuator in Sector 7
• There is a white box on my medm screen

16
Benefits of a relational database approach

• Utilizing relational database technology and
  defining connections between the entities yields
  the benefits of extensive querying capabilities
  through the tables of data.
• Immediate tracing of a fault to the root cause
• Predicting what applications will break when a
  module is removed
• Locating every instance of a particular device
• Convenient and expedient i.e. really cool
  tools encourage wide participation in keeping the
  data current

17
Three Relationships of Components
Control/Housing/Power
18
How do we get there?

• Two approaches
• Descriptive (describes what is installed)
• Prescriptive (defines what is to be installed)
• An exhaustive prescriptive solution has not been
  accomplished (as far as we know)
• We think an exhaustive descriptive solution is
  within reach
• Having an exhaustive descriptive solution may
  alleviate some difficult requirements on a
  prescriptive solution (e.g. history)
• An exhaustive descriptive solution and a partial
  prescriptive solution may certainly co-exist.
• Question Are an exhaustive descriptive solution
  and an exhaustive prescriptive solution
  redundant?
• If yes, not until someone succeeds
• If no, then we all ought to do the easy one first

19
How do we get there?

• We feel that everyone can benefit from an
  exhaustive descriptive approach and that it is
  complementary to the prescriptive efforts being
  undertaken.

20
What do I want?

• An identification of those areas where there is
  the most overlap of needs.
• An intense collaboration to fulfill those needs
  in a way that can be extended to accommodate site
  specific requirements.
• If we can leverage enough resources, we feel that
  it is entirely possible to deliver an exhaustive
  descriptive approach (that can be used at any
  EPICS site) by the end of 2005.
• This does not obviate the need for prescriptive
  solutions. In fact, it might make them easier.