2 Back Of The Envelope Estimation Flashcards
1
Q
What is high availability?
A
It’s a ability of a system to be continuously operational for a desirably long period of time.
2
Q
Service Level Agreement (SLA)?
A
It’s an agreement between service provider and customers, and this agreement formally defines the level of uptime your service will deliver.
3
Q
QPS, DAU, peak QPS
A
QPS: - query per second;
DAU: - daily active users;
Peak QPS: - 2 * QPS.
4
Q
99.9% downtime per year
A
8.77 h
5
Q
99.99 downtime per year
A
52.6 min
6
Q
99.999 downtime per year
A
5.26 min
