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Interview concept

What are quorum reads and writes?

Quorum reads and writes require responses from a chosen number of replicas before an operation succeeds. With N replicas, a design often chooses read quorum R and write quorum W so R plus W exceeds N, making the read and write sets overlap.

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Summary

Key takeaways

Quorum Reads and Writes - ExtraBrain is part of ExtraBrain's local-first Mac workflow for live interviews, meetings, transcription, provider control, and responsible AI use.

Page focus

Quorum reads and writes require responses from a chosen number of replicas before an operation succeeds. With N replicas, a design often chooses read quorum R and write quorum W so R plus W exceeds N, making the read and write sets overlap.

Platform fact

ExtraBrain has 1 current public platform family, macOS, with support for 2 Mac CPU families: Apple Silicon and Intel.

Data-flow fact

ExtraBrain has 3 configurable data paths to review before sensitive work: local Parakeet transcription, local Gemma 4 where installed and compatible, and external providers you choose.

Interview concept

How it works

The overlap rule

When R plus W is greater than N, every successful read contacts at least one replica that acknowledged the latest successful write.

Tunable consistency

A larger write quorum strengthens write durability, while a larger read quorum can detect newer versions at the cost of latency and availability.

Conflicting versions

Quorum overlap does not solve concurrent writes by itself, so systems still need versions, timestamps, vector clocks, or application-level merging.

Failure budget

An operation remains available only when enough replicas are reachable to satisfy its chosen quorum.

Interview concept

Practice the tradeoffs with ExtraBrain

Calculate the quorum live

Sketch N, R, and W values and explain a failed replica while ExtraBrain tracks the diagram and transcribes the consistency argument.

Keep architecture practice private

The Mac-native workflow supports local transcription and local history, which limits how much design-session data must leave the machine.

Compare with your chosen AI

Ask compatible on-device Gemma or a provider you control to challenge the tradeoff. The free core can capture both solo rehearsal and peer meetings.

Interview concept

Responsible use

Use any live AI assistant only where interview, workplace, school, and platform rules allow it. Do not use generated answers to misrepresent your skills, experience, or authorship.

FAQ

Common questions.

Short answers for people and crawlers comparing ExtraBrain with other live AI assistants.

Why should R plus W be greater than N?

It forces the read set and latest successful write set to overlap at one or more replicas.

Do quorums guarantee linearizable reads?

Not automatically. Concurrent writes, sloppy quorums, stale version metadata, and repair timing can still require stronger coordination.

How do quorum sizes affect availability?

Larger quorums need more reachable replicas, so they can improve consistency while reducing availability and increasing latency.