Illustrative scenario · Energy

The historian went dark at 2:14 a.m. It was back before shift change.

One control engineer, one live outage on a power plant's transformer bank, no vendor ticket, no 2 a.m. page to the one person who usually knows how.

Power generation · combined-cycle Aveva System Platform + Historian NERC CIP data retention

A composite scenario grounded in real historian failure modes — not a specific customer.

11 min
to resolution
0 bytes
left the plant
1 engineer
no escalation
Context

A summer demand peak, one engineer on shift, and the one person who'd know is on vacation.

A 450 MW combined-cycle plant feeding the grid through a step-up transformer bank. Aveva Historian logs everything on it — required reading for NERC CIP compliance, not just operations. Tonight it's one control engineer covering the whole site, and the admin who usually untangles Historian problems is on vacation.

At 02:14, an alarm fires: Historian stops storing tags from the transformer bank. Not a safety event — but a blind spot during a demand peak the grid operator is watching, with a compliance clock quietly running underneath it.

02:14
Alarm — Historian stops storing GSU tags
02:16
Engineer opens Rung on the terminal by the HMI
02:20
Root cause found, fix approved
02:25
Tags resume, incident logged
Actions

The engineer describes the symptom. Rung does the digging.

Every read is automatic and local. The one step that changes something on the server is flagged, and waits for a yes. →

Ask

Plain language — no log paths, no vendor jargon.

Diagnose

Parses the Historian log locally, in seconds.

Isolate

Read-only disk check finds the runaway log.

Fix & verify

Approved, then confirmed with a read-only query.

rung — operator terminal
rung ❯
✻ Thought for 2.8s
╭─ ⚙ parse_log
│ path=D:\ProgramData\ArchestrA\Historian\smc.log
╰─
9 errors since 02:14 — most recent: storage subsystem offline, write failure
╭─ ⚙ run_command (read-only)
│ df -h D:\
╰─
D:\ (historian data volume) — 100% used, 0 bytes free
└─ OPCUATrace_20260714.log growing ~40 MB/min — left on from a prior vendor session
╭─ ⚙ run_command
│ clear OPCUATrace_*.log · restart HistorianStorage
Allow? [y] allow once · [a] always · [n] deny
2.1 GB reclaimed · HistorianStorage restarted
╭─ ⚙ historian_query (SELECT-only)
│ GSU_Transformer.* — last 5 rows
╰─
Tags resumed at 02:24 — 10s gap, no rows lost beyond it.
Root cause: verbose OPC UA tracing left enabled filled the
data volume. I've noted a disk-usage alarm for next time.
Result

Tags resumed before the shift-change handoff.

The engineer never left the terminal, never escalated, and never sent a byte of plant data anywhere it shouldn't go.

11 min
Total time to resolution
vs. ~95 min typical for this failure mode
0
Bytes of plant data left the site
diagnosis ran locally, read-only by default
1
Engineer needed
no vendor ticket, no 2 a.m. page

The fix and the reasoning behind it are sitting in the session transcript — it becomes the runbook entry for the next engineer who hits the same alarm, senior admin or not.

Why this is better than without Rung

What the same incident usually costs, and what it cost here.

An engineering estimate, not a lab result — every plant, historian, and failure mode differs. It's the shape of the problem Rung is built to compress.

Without Rung
60–120 min
With Rung
11 min
CriteriaWithout RungWith Rung
First look at the logs 15–30 min opening ArchestrA logs by hand Under a minute — parsed and summarized automatically
Who's needed Often the one person who "knows the historian" — not always on shift Whoever is on duty, on the terminal they already have
Escalation path Page a senior admin, or open a vendor ticket (hours, per typical SLA) None required for this incident
Data leaving the site Sometimes — log excerpts pasted into a ticket or a general AI chat tool None — diagnosis runs locally, read-only by default
Compliance exposure Risk of a NERC CIP data-retention gap needing formal reporting Resolved inside the safe window
Total time to resolution 60–120+ min, sometimes into the next shift 11 min

This is a composite scenario grounded in real Historian failure modes, not a specific customer's numbers — every plant and incident differs. A control engineer is commonly a six-figure loaded resource on a site where an hour of blind spot during a demand peak carries real risk; the value here is measured in time and exposure avoided, not a fabricated dollar figure.

See it on your own historian

Bring this workflow to your plant.

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