PI System Management Best Practices Bryan S. Owen P.E. OSIsoft Field Service
Jan 21, 2016
PI System Management Best Practices
Bryan S. Owen P.E.OSIsoft Field Service
Focus on BenefitsImprove
SustainAssess
Change Management Interacts with System Management!
Change Management and Continuous Improvement
Typical PI Improvement Projects• Server Upgrades• Custom Applications• Raw Data Collection• Performance Calculations• Layered Data Structures• Desktop Deployments• Skill Development
PI Server Upgrade
Stage Upgrade on Spare Platform• Preferred O/S – Windows 2K
• Windows Domain Membership
• Test with PItoPI or Parallel Interfaces
Review PI Timeout Table• Maxupdatequeue, Totalupdatequeue, Readtimeout
• http://support.osisoft.com/FieldService/service_downloads.htm
Interface Status Watchdog (Optional)• “flatline” detection
• optional status change for input points
Custom Application Guidelines
Preferred Core PI Technology• SQL (OLEDB Provider)• OPC Server• SDK/API
Deployment Hints• Dedicated PI User Name• Identify all Inputs and Outputs to PI• Assign DataOwner on Output Points
RtPM Pyramid
Data Collection from Inside and Outside the Corporation
Execs Look for Equipment, Plants, Products, not Tags
Aggregation, Reconciliation, Calculation, Cases
Get the Information to People Who Need It
People Need Pictures, Graphs, Trends
Without Action, there is no Benefit
Gather
Assign Context
Analyze
Distribute
Visualize
Act
Connectors or Interfaces?
Integrated Data Source• Archive is provided
by source system• No data replication • PI queries redirected
to source host
Constraints: scalability, connection latency
Hot: OLEDB Connector
Decoupled Data Source• No archive retention
burden on source host• Scheduled replication• PI queries resolved
locally
Constraints: scan rate and out of order data
Hot: OPC Interface
Data Source Reconciliation
Periodic Discovery• Automatic Point Synchronization
(yes, OPC connector!)• Dedicated workstation is suggested
Point Deletion• Server concordance check
(SMT advanced search…getpointssql)• Alternative: set ptaccess=“o: g: w:”
Point Type Selection…Float16 vs Float32
FLOAT32 is easy on the administrator but…• No under/over range sanity check
(unless a supported by the interface).
• Dirty zero affects aggregates differently(not reflected in percent good, use Totalizer with zerobias).
• Performance penalty (~2x archive i/o).
FLOAT16 rules of thumb…• Well defined zero and span required.• Large scale systems >50,000 pts.• Sub second data collection.• High data density applications (PI profile points).
Interface Accuracy
Scan Class Schedules• Avoid schedule collisions
Dedicated Instances• Load balancing and isolation• Event triggers and outputs• Special handling
(stopstat, watchdog list)
Report all changes to PI• Minimize Excdev (zero is ok!)• Buffer recovery is constraint
Compression Guideline
Ideal: set based on process specification• usually <1% compression deviation
Easy: use rated instrument precision• Excess archiving is a potential process
issue or sampling limitation.• If possible, resolve “noise” at the source
(filter may be an appropriate remedy).
RtPM Pyramid
Data Collection from Inside and Outside the Corporation
Execs Look for Equipment, Plants, Products, not Tags
Aggregation, Reconciliation, Calculation, Cases
Get the Information to People Who Need It
People Need Pictures, Graphs, Trends
Without Action, there is no Benefit
Gather
Assign Context
Analyze
Distribute
Visualize
Act
Layered Data Structures in PI
Base• Digital Sets• Headings• Aliases• Properties• Modules
Archive• Batch, UnitBatch/SubBatch, Transfers
Digital Sets
System set is global• Applies to all points• Important factory defaults include
• “Shutdown”, “Intf Shut”, “I/O Timeout”
Digital points preferred over string tags• Enables multistate symbols and trends• Create dedicated state sets• Include placeholders for volatile sets
PI Headings…mutant Digital Sets!
• Name, Level and Description• Level starts at 1• Discontinuous sequences ok• Optional Module or SubBatch property
PI Alias Collections…Cached point lists
• Organize points by module• Leverage utility with alias names• Multiple aliases for the same tag ok• Join tags from any number of servers
Alias “aware” applications:• ACE, Batchview, MDB Editor• OLEdb Provider, OPC Server, SDK/API
PI Property Collections…Named Value Tables
Collections in free format hierarchal structures.
Associate nominally “static” properties with a Module.
Stored in Archive when assigned to a Batch or Transfer Record.
PI Module Collections…File System for PI
Free format hierarchy, a PI module may “link” to multiple collections.
Access rights depend on DBsecurity and the root module owner.
Versioning and query control based on “effective” date.
“isPIunit” creates archive point for unitbatch recording.
Layered Data Structures in PI…Management Tips
Restrict write access (DBsecurity default)• Digital Sets – PIDS• ModuleDB – PIModules, PIHeadingSets
Standardize Digital Sets across an Enterprise• Especially useful with PItoPI implementation
Configure ModuleDB with SDK/VB scripts:• Transmission Line Demo
RtPM Pyramid
Data Collection from Inside and Outside the Corporation
Execs Look for Equipment, Plants, Products, not Tags
Aggregation, Reconciliation, Calculation, Cases
Get the Information to People Who Need It
People Need Pictures, Graphs, Trends
Without Action, there is no Benefit
Gather
Assign Context
Analyze
Distribute
Visualize
Act
Server CalculationsPerformance Equation StudyOver 15 servers & 5500 expressions
• …expression lengthMedian 50 characters, 95% < 162, Max=2851!
• …archive function calls (~10% of total )Median time span <9 hrs, Max since 1970!
• …nesting levels (excluding circular logic)One Level 25%, Two Levels 9%, More 2.5%
• …variables per expression (max=156!)
Performance Equation Study…Conclusions
Primary Usage Analysis• simple transformations…y=mx+b, steam tables• data smoothing…tagavg, medianfilt• state detection / signal selector…if then else
Conclusions• 80% of PE expressions are appropriate• 20% in need of redesign
• Implement in ALARM or TOTAL processor• Logic or schedule more appropriate for ACE
Performance Equation Tips
Develop Expressions on PI Desktop• Datalink “Expression Calculation”• Processbook “PI Dataset”
Don’t implement on production servers until proven!
Scheduling Options• Run simple transforms at raw scan rate• Uniint event triggers
Event=‘motorstatus’ increment, (run on 0 -> 1 transition)
• Enable Recalc for expressions with LAB inputs
RtPM Pyramid
Data Collection from Inside and Outside the Corporation
Execs Look for Equipment, Plants, Products, not Tags
Aggregation, Reconciliation, Calculation, Cases
Get the Information to People Who Need It
People Need Pictures, Graphs, Trends
Without Action, there is no Benefit
Gather
Assign Context
Analyze
Distribute
Visualize
Act