> ## Documentation Index
> Fetch the complete documentation index at: https://docs.breakscale.tech/llms.txt
> Use this file to discover all available pages before exploring further.

# Multi-region failover

> What a failover actually costs you

Two regions, one serving. Crash the active one and every request fails until failover lands.

## What to watch

Crash the US API. For five seconds every request fails while the router notices, then Europe picks it all up. Only one region takes traffic at a time, so this pair buys you survival, not extra capacity: at 4x the active region melts while the standby sits at zero.

## What it is made of

| Component | Count |
| --------- | ----: |
| Client    |     1 |
| Database  |     2 |
| Region    |     1 |
| Service   |     2 |

## Under load

Measured by running this design through the simulator at multiples of its own offered rate of 250 requests a second. Twenty seconds of simulated time, one fixed seed, so the same numbers come out every time.

<Note>This design holds 375 requests a second with 0% errors. At 500 it is losing 23% of them.</Note>

| Offered | Goodput |     p99 | Errors |
| ------: | ------: | ------: | -----: |
|     250 |     232 |  76.9ms |     0% |
|     375 |     384 | 169.9ms |     0% |
|     500 |     393 | 246.3ms |  23.2% |
|     625 |     388 | 260.2ms |    40% |
|     750 |     392 | 253.4ms |  48.7% |
|    1000 |     393 |   247ms |  61.8% |
|    1500 |     392 | 250.5ms |  73.1% |
|    2000 |     391 | 259.9ms |  80.6% |

<Card title="Open this example" icon="play" href="https://breakscale.tech">
  Load **Multi-region failover** from the Examples menu and drag the traffic slider yourself.
</Card>