Happy Wednesday! Every system design review eventually lands on the same question: what happens when this one thing breaks? Today’s word — redundancy — is how architects answer that question in English, and it’s a word that shows up in nearly every design doc, incident postmortem, and infra standup you’ll sit through.
📖 Word of the Day: Redundancy
- Word: redundancy
- IPA: /rɪˈdʌn.dən.si/
- Vietnamese meaning: tính dự phòng — có thêm bản sao hoặc thành phần dự trữ để hệ thống vẫn hoạt động khi một phần bị hỏng
- Example sentences:
- “We added redundancy to the database layer so a single node failure never takes the whole app down.”
- “The team debated whether the extra redundancy was worth the cost, or if it was overengineering for traffic we don’t have yet.”
- “Losing the primary region wasn’t a disaster, because redundancy across two other regions kicked in automatically.”
Listen and practice pronunciation:
Vocabulary Table — System Architecture
| Phrase | Vietnamese | Example |
|---|---|---|
| Horizontal scaling | mở rộng theo chiều ngang | ”We handle Tet traffic spikes with horizontal scaling — just spin up more servers.” |
| Vertical scaling | mở rộng theo chiều dọc | ”Vertical scaling meant upgrading the same box instead of adding new ones, and we hit a ceiling fast.” |
| Failover | chuyển đổi dự phòng khi có sự cố | ”Failover to the backup cluster happened in under ten seconds, so most users never noticed.” |
| Fault tolerance | khả năng chịu lỗi | ”Good fault tolerance means the checkout flow still works even if one payment provider is down.” |
| Load balancer | bộ cân bằng tải | ”The load balancer spreads incoming requests across five app servers.” |
🗣 Pronunciation Guide
“Redundancy” breakdown — /rɪˈdʌn.dən.si/:
- Four syllables: rih-DUN-duhn-see
- Primary stress is on the second syllable: rih-DUN-duhn-see
- The “dun” in the middle rhymes with “sun” — don’t soften it to “dahn”
- The ending “-cy” is a light “see,” same sound as in “frequency” or “urgency”
Practice sentence (read aloud 3x):
“We built in enough redundancy that losing one server is a Tuesday afternoon problem, not a wake-everyone-up-at-3-a.m. problem.”
Read it slowly the first time to get every syllable of “redundancy” right, stress “DUN” clearly the second time, then read it at natural speed the third time.
✍️ Exercise 1: Fill in the Blank
Fill each blank with one term: redundancy, horizontal scaling, vertical scaling, failover, fault tolerance, load balancer.
- “When the primary database went down, _______ kicked in and traffic moved to the replica automatically.”
- “We ran out of room to upgrade the single server, so we switched from _______ to _______.”
- “The _______ distributes every incoming request across the healthy servers in the pool.”
- “Without enough _______, one bad server can quietly take down the entire checkout flow.”
- “Good _______ means the system survives losing a component instead of falling over completely.”
Show answers
- failover
- vertical scaling, horizontal scaling
- load balancer
- redundancy
- fault tolerance
✍️ Exercise 2: Translate to English
Translate these Vietnamese sentences using today’s vocabulary.
- “Chúng tôi thêm một bản sao dự phòng cho database để tránh mất dữ liệu.”
- “Khi máy chủ chính gặp sự cố, hệ thống tự động chuyển sang máy chủ dự phòng.”
- “Bộ cân bằng tải giúp chia đều lưu lượng truy cập cho tất cả các server.”
Show answers
- “We added redundancy to the database to avoid data loss.”
- “When the primary server fails, the system automatically fails over to the backup server.”
- “The load balancer helps distribute traffic evenly across all the servers.”
💬 Idiom of the Day: “Better safe than sorry”
- Vietnamese meaning: cẩn tắc vô áy náy, phòng bệnh hơn chữa bệnh
- Example 1: “We spent an extra sprint on redundancy for the payment system — better safe than sorry when real money is involved.”
- Example 2: “The extra backup region felt unnecessary until the outage last month. Better safe than sorry.”
📺 Recommended Watching
- ByteByteGo — short, visual breakdowns of real system design problems, including redundancy and failover patterns
- Gaurav Sen — deeper system design interview walkthroughs with clear spoken explanations
- YouGlish — hear “redundancy” pronounced across real technical talks
🎯 Daily Challenge
Pick one app you depend on every day — your bank, Grab, or a messaging app — and say out loud in English, in one sentence, where you think its biggest single point of failure is and what redundancy you’d add if you were the architect. Thirty seconds, out loud, no notes.