Go global
Serve users on other continents from Series C, with a second region, GeoDNS, local copies of your Design, and data that survives a Region outage.
Use this guide when you reach the Series C Era and users abroad are slow, or when you need to survive a Region outage.
From Series C, users live in four regions: North America, Europe, Asia-Pacific, and South America. Each region grows or shrinks on its own Apdex. Every user still enters your home region at first, and a far user pays the round trip across the ocean twice for each request.
Find out who is slow#
Select Users on the HUD to open Why users leave. Look for rows from far regions.
Select the Users Node and open Requests. Compare the mean latency of each kind with the figures before Series C.
Read the Series C page for each region's share of your users.
No change to capacity fixes this. The time is the distance. You must serve users from a region near them.
Open a second region#
Research Multiple regions. It needs Multiple zones.
Find the region tabs at the top of the board. Closed regions show as + EU, + APAC, and + SA.
Click the region with the most slow users. Its tooltip shows the price. The game opens the region and adds its own Users Node.
Click the new tab to see that region's board.
Send users to their region#
Research GeoDNS. Without it, every user still enters the home Users Node. With it, each region's users enter their own Users Node, or the nearest one that is up.
On the new tab, place a Load Balancer and App Servers, and link the region's Users Node to them.
Select a Node and open its Region section to move it to another open region. A Node that moves restarts.
The Payment Provider, LLM API, Push Provider, Auth Provider, CDN, Analytics, and Payments serve every region. Do not copy them.
Decide where the data lives#
An App Server abroad that calls the home Database pays a cross-region round trip on every query. Pick one pattern for each data Node:
| Pattern | How | Tradeoff |
|---|---|---|
| Read locally, write home | Place a Read Replica in the new region. Link writes to the home Database. | Fast reads. Writes cross the ocean. Some reads come back stale. |
| Leaderless store | Wide-column Store with Regions set to Spread. | Local quorums. Eventual consistency across regions. |
| Consensus store | Distributed SQL with Regions set to Spread. | Correct everywhere. Slow writes. Much more Burn. |
A spread store runs nodes in up to three regions and bills for each. Use Distributed SQL for checkouts, and a leaderless store for feeds. See The data tier.
Copy the Design with a Mirror#
Building each region by hand is slow and drifts. With Infrastructure as code, you mirror one region into another.
Click Mirror next to the region tabs.
Pick an IaC tool. Then, under "Mirror … into", pick the target region. Each button shows its price.
For each data Node, pick how the Mirror copies it: Read replica, Own primary, Replicate, or Call source.
Click Apply. The new Nodes serve after the apply time.
Later, a dot on a tab shows that the region has drifted from its source. Apply again, or keep the change as an override.
GitOps syncs Mirrors on its own, all at once or Staged.
Survive a Region outage#
A Region outage takes down every Node in one region, except global Components and stores spread across enough regions.
Keep App Servers in at least two regions, with GeoDNS on.
Keep the data that the other region needs available there: a spread store, or a replica you can serve from.
Keep spare capacity in each region. The users of the failed region move to the nearest live one.
Cut the user hop#
Anycast takes 20 ms off the user hop everywhere.
HTTP/3 cuts the hop to distant users by 20%.
Calls between regions also cost egress. Keep each region's App Servers calling their own data where you can.
Check the result#
Open Why users leave again. The far-region rows must shrink.
Check that Apdex on the HUD returns to its target.
Before the IPO, the DR drill fails your home region on purpose. See Prepare for an Exit.
Practice#
The Far Away Sandbox puts half your users outside North America. Get API reads under its limit on average. The Missed Write Sandbox asks every API read to see the latest write.
Related#
GeoDNS, Leaderless replication, and RPO and RTO in the glossary.