SLA

• service level agreement
• 制定
  • 吞吐量
  • 响应时间
  • 可用性降级方案
• SLA估算

  Availability %	Downtime per day	Downtime per year
  99%	14.40 minutes	3.65 days
  99.9%	1.44 minutes	8.77 hours
  99.99%	8.64 seconds	52.60 minutes
  99.999%	864.00 milliseconds	5.26 minutes
  99.9999%	86.40 milliseconds	31.56 seconds