iPhone and iPad · Version 1.5

SLO/SLA Calc

Know the Device. Build the System. Evaluate the Mission.

Expose every Device assumption, carry its availability and MTBF into reusable topologies, and estimate whether the complete design can finish a time-bound mission without interruption.

Explore version 1.5

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What’s new in 1.5

From Device assumptions to mission confidence

Version 1.5 makes Device Availability auditable, preserves MTBF provenance through reusable designs, and adds a distinct non-repairable Mission Reliability model.

Transparent Device modelReview base MTBF, power benefit, logistics, EOL delay, support eligibility, repair time, and modeled restoration time.
Editable assumptionsInspect and adjust app-wide generic MTBF and restoration defaults used for new Device calculations.
Named Device reuseCarry a saved Device name, availability, and MTBF source into Series, Parallel, N:M, and Cross-Connected Components.
Preserved provenanceKeep manufacturer-provided or generic-estimated MTBF data attached through Blocks, Systems, reports, and editable .slosla files.
Mission ReliabilityEstimate uninterrupted success for a saved Device, Block, or System over a mission measured in hours, days, or weeks.
Explicit approximationsUse strict MTBF validation or intentionally estimate availability-only inputs with a restoration-time or reference-period assumption.
Decision evidenceCompare Mission Success, Interruption Risk, any-Component failure probability, expected failures, and the weakest contributor.
Expanded guidanceFollow a richer Guided Tour and Reference material covering RBD translation, System handoffs, formulas, limitations, and worked examples.

Transparent Device Availability

See what the percentage is built from.

Start with manufacturer MTBF or a documented generic estimate. Then see how redundant power, spares, logistics, EOL sourcing, support, and hands-on repair time affect the result.

Support benefits are applied only when their configured threshold is met, and every assumption remains visible in the calculation breakdown.

Device Availability calculation and transparent restoration-time breakdown on iPad — Operational availability with the assumptions visible beside the inputs.

Reusable Device data

Calculate once. Reuse with context.

Save a Device by name, then select it directly in a Series, Parallel, N:M, or Cross-Connected Component row.

The Component receives a snapshot of the Device name, calculated availability, MTBF, and source so the larger design remains reproducible.

Saved Router-1 Device reused in two paths of a Parallel topology on iPhone — Named Device data carried into each topology path.

Mission Reliability

Ask whether the design can finish the mission.

Availability measures service over time with restoration. Mission Reliability estimates uninterrupted success during one bounded period with no repair during the mission.

Use stored MTBF when available, or explicitly choose an approximation for availability-only inputs. The app labels the data quality and identifies the weakest contributor.

Mission Reliability results with mission success, interruption risk, expected failures, and weakest contributor on iPad — A distinct non-repairable model for time-bound mission success.

Live Modeling

Break the model before the real System breaks.

Apply temporary Block, Component, and switch failures without changing the saved design. Remaining Availability and service delivery recalculate immediately.

Animated Red and Blue paths show which inputs survive. Shared connections become Purple, and a single-output switch selects one healthy handoff.

Live Modeling workspace with System status, animated input flows, topology, and failure controls on iPad — One workspace for topology, flow delivery, and deterministic failure testing.

Compare design outcomes

Turn alternatives into a decision.

Compare two saved Systems over the same period to see availability difference, downtime reduction, and design size.

Add an optional SLO to see which alternatives meet the target while detailed error-budget analysis remains available in Insights.

Side-by-side System availability and downtime comparison on iPad — A decision summary explains the modeled advantage.

Example lab

Import two Systems. Inspect the difference.

These compact reference designs demonstrate the portable .slosla model and a topology detail that only becomes visible at very high availability.

Direct handoff

SYS-1

99.99999775015%

A1A2

Direct

N1N2

Two 99.99% paths feed two 99.995% paths through a one-to-one Direct handoff.

Download SYS-1

Fully Cross-Connected

SYS-2

99.999998%

A1A2

Full Cross

R1R2

Four 99.99% Blocks remain available through a Fully Cross-Connected Handoff.

Download SYS-2

Version 1.5 walkthrough

Know the Device. Build the System. Evaluate the Mission.

Follow the path from a transparent Device calculation into a reusable Parallel topology, a time-bound Mission Reliability result, Live Modeling, and an evidence-based System comparison.

Get SLO/SLA Calc

Complete toolkit

Availability decisions in one place

Advanced topology

Calculate Series, Parallel, N:M, and Cross-Connected configurations with individual Component availability.

Transparent Device Availability

Use manufacturer MTBF or a documented generic estimate and inspect every restoration-time assumption behind the result.

Reusable Device provenance

Carry saved Device names, availability, MTBF, and data source into topology Components and portable System files.

Mission Reliability

Estimate uninterrupted success over a bounded mission using stored MTBF or an explicit availability-only assumption.

Mission risk evidence

Review interruption risk, expected failures, any-Component failure probability, weakest contributor, and input data quality.

Downtime lookup

Translate any availability percentage into downtime per day, week, month, or year.

SLO error budget

Compare a saved design with its target SLO and interpret remaining or exceeded downtime budget.

System comparison

Compare two complete Systems and quantify availability improvement, downtime reduction, and design complexity.

Live Modeling

Fail Blocks, internal Components, and switches while Remaining Availability and service delivery update in real time.

Full-screen canvas

Expand Live Modeling into a dedicated interactive view that adapts to portrait or landscape on iPhone and iPad.

Visible input flows

Trace Red and Blue through surviving paths; Purple identifies a connection carrying both inputs.

Editable Systems

Share, export, preview, and safely import complete .slosla designs without overwriting local work.

Ideal Path

Represent a deliberate passive bypass explicitly without turning every 100% Block into a non-failable element.

Visual reports

Verify the continuous architecture, then share availability, downtime, Block snapshots, and the diagram as a PDF.

Guided learning

Follow Device reuse, RBD translation, Stage handoffs, Live Modeling, SLO, comparison, and Mission Reliability workflows.

Local-first storage

Calculations and saved designs remain on the device. Files leave only when you choose to export or share them.

iPhone and iPad

A workspace that fits the device

Focused navigation on iPhone, expanded decision context on iPad. Version 1.5 keeps the assumptions, topology, mission result, and comparison readable at each step.

Transparent Device Availability breakdown on iPhone — Inspect every Device assumption

Saved Router-1 Device reused in a Parallel topology on iPhone — Reuse named Device data

Mission Reliability result on iPhone — Evaluate a time-bound mission

Live Modeling workspace on iPad — Trace the surviving System

System comparison and decision summary on iPad — Compare design outcomes

How it works

From Device assumptions to a defended decision

01
Model the Device. Choose the MTBF source, enter restoration inputs, and verify the complete calculation breakdown.
02
Save the evidence. Preserve the Device name, availability, MTBF, source, and assumptions in a reusable Block.
03
Translate the RBD. Arrange required dependencies in Series, independent alternatives in Parallel, and capacity or cross-connect behavior explicitly.
04
Connect the Stages. Use ordered Stages, Parallel Groups, Direct handoffs, Full Cross handoffs, and optional output switches.
05
Test resilience. Run Live Modeling, fail Blocks or Components, and watch the surviving paths and Remaining Availability.
06
Evaluate the mission. Set a duration and review Mission Success, Interruption Risk, expected failures, and data quality.
07
Compare and share. Check SLO fit, compare alternatives, generate a PDF, or export an editable .slosla System.

Private by design

Your designs stay on your device.

SLO/SLA Calc works offline and does not collect analytics, show ads, track users, or automatically send calculations and saved designs to a server. PDF and .slosla files leave only when you choose to export or share them. Read the privacy policy.

Support

Questions, feedback, or a real design case?

Email support@sloslacalc.app. Practical feedback from engineers, architects, and operators directly shapes the app.