SLA 、SLO ＆ SLI

SLA

SLA,Service-level agreement It's a service level agreement . It's an agreement between merchants and customers , It is an indicator of service availability . Specify what requirements businesses need to meet for the services they deliver , For example, software performance , response time , stability , Quality, etc . Each of the requirements is determined by the corresponding SLO To describe , therefore SLA yes SLO Set .

SLA How many are usually used 9 To define , according to 1 Every... Month 5 Minutes visit 100 The failure probability of secondary service .
1 The visit probability within months is ：130 God 24 Hours 60 minute /5 = 8,640 Statistical probability
1 The number of visits in a month is ：8640100 = 864,000 Secondary service

1. stay 3 individual 9 Under the circumstances ： 864,000 *(1-0.999） = 864 Secondary failure
2. stay 4 individual 9 Under the circumstances ： 864,000 *(1-0.9999) = 86.4 Secondary failure
3. stay 5 individual 9 Under the circumstances ： 864,000 * (1-0.99999) = 8.64 Secondary failure
   Many businesses are hard to do 5 individual 9 Standards for , It needs very perfect infrastructure and extremely high IT Personnel service level .

SLO

SLO,service level objective Is the service level goal . Is the usability goal of the product , As a benchmark benchmark The basis of . such as Round Trip Time / RTT The average compilation time after file changes cannot exceed 2S, It's just one. SLO. If RTT exceed 2S, It does not meet this SLO.

SLI