Conas a dhéanann tú córais a dhearadh a láimhsíonn theipeanna go geal?

Question

Accepted Answer

Ag scála, **tá teipeanna dochéachta** — tuiteann freastalaithe, theipeann líonraí, éiríonn spleáchtais ar fáil. Dearadh do theipeanna a chiallaíonn córais a thógáil a **fhulaingíonn agus a tharrthálann ó theipeanna go geal** seachas a bheith ag glacadh leis go bhfuil gach rud ag feidhmiú. Tá sé seo riachtanach do chórais iontaofa.

## Dearadh do theipeanna (an meincíochtar)

```text
ASSUME things WILL fail → at scale, failures are NORMAL, not exceptional:
  → servers crash, networks partition, disks fail, dependencies go down, traffic spikes
  → design systems to EXPECT and HANDLE failures gracefully (not assume everything works)
→ "everything fails all the time" → build resilience in.
```

## Teicnící athléimneachta

```text
✓ REDUNDANCY → multiple instances, no single point of failure (failover to healthy ones)
✓ RETRIES (with backoff) → retry transient failures (with exponential backoff + jitter to
  avoid overwhelming a recovering service)
✓ TIMEOUTS → don't wait forever for a failing dependency (fail fast)
✓ CIRCUIT BREAKERS → stop calling a failing service temporarily (prevent cascading failures;
  give it time to recover) → fail fast and fall back
✓ GRACEFUL DEGRADATION → reduced functionality vs total failure (e.g. show cached/partial
  data if a service is down)
✓ FALLBACKS → a default/alternative when something fails
✓ BULKHEADS / isolation → contain failures (one part failing doesn't sink everything)
```

## Teipeanna cascadh a sheachaint

```text
⚠️ CASCADING failures → one failure triggers others (e.g. a slow service exhausts callers'
  resources → they fail too → spreads)
→ prevent with: timeouts, circuit breakers, isolation/bulkheads, load shedding, backpressure
✓ MONITORING/alerting → detect failures fast; test failure scenarios (chaos engineering)
```

## Cén fáth a bhí ann

Tá sé luachmhar tuiscint a bheith agat ar conas córais a dhearadh a láimhsíonn theipeanna go geal toisc **go bhfuil teipeanna dochéachta ag scála**, agus go bhfuil dearadh ar a shon riachtanach do chórais iontaofa, mar sin is eolas córas-dhearaidh tábhachtach atá ann.

An meincíochtar bunúsach — **glacadh leis go dteipfidh ar rudaí** (toisc ag scála, tá teipeanna gnáth, ní eisceachtúil — tuiteann freastalaithe, deighiltear líonraí, téann spleáchtais síos) agus córais a dhearadh le bheith ag súil le teipeanna agus a láimhsiú go geal seachas a bheith ag glacadh leis go bhfuil gach rud ag feidhmiú — is é seo bonn an chóras iontaofa, gabhta sa phrionsabal go