Search the practice set
126 questions, 454 terms and 400 topics in 20 areas.
20 results for “Parallel Run”
Parallel Run
Running the old and new systems side by side on the same inputs and comparing outputs, before the new one is trusted.
Architecture Cost Model
A calculation, made during design, of what an architecture will cost to run at expected and at peak volume.
Artifact Signing
Cryptographically signing build outputs so that deployment can verify what is being run was produced by the expected pipeline from the expected source.
Block Storage
A virtual disk attached to one instance at a time, presented as raw blocks and formatted with a filesystem — the storage databases and stateful workloads run on.
Blue-Green Database Schema
The constraint that makes fast rollback actually work — both application versions must be able to run against one schema at the same time.
FinOps
The practice of giving engineering teams visibility into and accountability for the cost of what they build and run.
Fitness Function
An automated check that an architectural characteristic still holds, run continuously rather than reviewed occasionally.
Idempotent Pipeline
A pipeline whose task can be re-run for the same input window any number of times and produce the same result.
Leader Election
The process by which a group of nodes agrees which one of them is currently in charge of a task that must not run twice.
Paved Road
A supported, opinionated default way to build and run a service, made easy enough that teams choose it rather than being required to.
Query-Based CDC
Detecting changes by repeatedly querying for rows modified since the last run — simple, universally available, and lossy in specific ways.
Zero-Downtime Migration
Changing a schema or system while it stays in service, by adding the new alongside the old, migrating, then removing the old.
A team says "backups run nightly and are retained for 30 days". You have one hour to assess whether they could actually recover. What do you check?
The checks, in the order that finds problems fastest 1. When was a restore last performed, and how long did it take? The single most informative question. If th
A team tells you backups run nightly and are retained for 30 days. What is missing from that answer?
What the interviewer is testing Whether you know that a backup is not a control until it has been restored — one of the most reliable ways to find an unrecovere
One service restarts unpredictably; another is slow with low CPU. Both run on Kubernetes. What are you looking at?
The two symptoms map to the two resource behaviours Unpredictable restarts → OOM kill. Memory is incompressible: a container exceeding its memory limit is kille
Run a threat model on a new payment integration: our service calls a third-party payment provider and receives webhooks. Where are the interesting threats?
Draw the boundaries first Three trust boundaries, and nearly every interesting threat lives on one of them: 1. User → our service (untrusted input, authenticate
You run active-active across two regions. The link between them fails. What should each region do, and what would you have designed differently?
The immediate answer Neither region can safely keep accepting writes to shared state, because neither can know it is the surviving side. Each sees one of two no
Parallel Run
Shadowing the old system to discover the rules nobody documented.
Resilience Testing
Exercising retries, breakers and fallbacks that are otherwise never run.
Showback & Chargeback
Making teams see, or own, the cost of what they run.