Cart or balance
Difficulty 3 of 5
A shop keeps carts and balances in two clusters of 3 copies. At 0:20 a fault cuts each primary off from its followers for 10 s. A shopper must always be able to add an item. A debit may be refused during the cut, but it must never be lost.
Options
- Accept writes everywhere, last write wins
- Accept writes only with a majority
- Carts accept and merge, balances need a majority
Goals and limits
- Lost writes
- none
- Error rate (Cart)
- under 0.1%
- Availability (Balance)
- at least 75%
- Monthly cost
- under 40 USD/mo
- Traffic
- 200 req/s
Concepts
How players did
Player results load from the server.