39. 指標標準化
標準化常見的 SLI,避免每次都重新評估
● Aggregation intervals: “Averaged over 1 minute”
● Aggregation regions: “All the tasks in a cluster”
● How frequently measurements are made: “Every 10 seconds”
● Which requests are included: “HTTP GETs from black-box monitoring jobs”
● How the data is acquired: “Through our monitoring, measured at the server”
● Data-access latency: “Time to last byte”
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42. SLO 的選擇
● Don’t pick a target based on current performance
○ 不能只看眼前,要從全局出發
● Keep it simple
○ 太複雜的匯總,會難以理解,同時會掩蓋系統性的變化
● Avoid absolutes (絕對值)
○ 要求擴展系統而沒有增加任何 latency ,或者永遠 Available 都是不切實際的
● Have as few SLOs as possible
○ 選擇足夠的 SLO 覆蓋系統屬性
● Perfection can wait (不完美也很美)
○ 隨著時間了解系統之後,進行 SLO 定義與調整。
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